There are various different categories of software. Quite a bit of software designed to implement technical solutions, particularly to networking, is discussed in the Techn's section. (For example, there is a section within the Techn's section about installing software, and under that section is a sub-section about installing software upgrades.) As another example, Anti-malware software is referenced by the section of the site that discusses Protection Software. Compression software may be referenced by a Bit Compression Software Tutorial available on this site. There is quite a bit of other software that is referenced by other sections of the site. This section is mainly for software that many people may use, but which is generally not very directly related to automatically offering automated services on computer networks.

Some methods of finding popular software:

[#opsys]: Operating Systems
Full-fledged base operating systems
BSD
OpenBSD, FreeBSD, NetBSD, Dragonfly BSD, Darin-based, others
OpenBSD
FreeBSD
NetBSD
Dragonfly BSD
Darwin-based
Others
Linux
Debian-based (including Ubunutu)
RedHat-based
Others
Microsoft code, and compatible/similar
Windows Emulation
ReactOS
Microsoft Windows
Others
Various other operating systems. Note that some operating systems by Microsoft may be in a different category.
DOS operating systems
Other OS platforms for computers
Firmware
Platforms for mobile devices
Live CDs
[#office]: Office software
For some options, see: TOOGAM's Software Archive of programs that work with common Office data, Wikipedia's comparison of default packaged programs
[#wordproc]: Word Processor software
AbiWord, OpenOffice Writer, KWord, Wordpad, Write, Google Docs, MS Word, MS Works, and more
[#spreadsh]: Spreadsheet software
Gnumeric, KSpread, OpenOffice Calc, Microsoft Excel
[#showsoft]: Presentation/Slideshow Creation/Presenting software
Impress, KPresenter, Microsoft PowerPoint
[#datbassw]: Database Software
SQL-based and other software
E-Mail clients

See also the Groupware software.

Information about some clients is covered in the section about handling E-Mail data. For programs that can support the IMF E-Mail format (which is the format most commonly used on the Internet), see E-Mail: User Agents. There may be additional information at Wikipedia's comparison of E-Mail clients.

Calendar/“Personal Information Manager (“PIM”)”/Groupware

Wikipedia's list of personal information managers

Evolution (“Novell Evolution”, “Ximiam Evolution”)
Evolution has been selected to be a part of the GNOME Office software. Wikipedia's information on Evolution for Windows describes a release for XP and newer.
[#mozcal]: Calendar projects based on code by Mozilla

Mozilla's “Calendar Project” has “led to the development of Sunbird” and Lightning, according to Wikipedia's page on “Mozilla Calendar Project”.

[#mozlghtn]: Mozilla's Lightning

Home pages: Mozilla's Lightning, Thunderbird addon: Lightning.

[#iceowl]: Iceowl
...
[#sunbird]: Mozilla Sunbird

See also: Iceowl. The home page for Mozilla Sunbird has stated, “This is the last public Sunbird release by the Calendar Project. We recommend upgrading to” (Thunderbird and) Mozilla's Lightning.” Mozilla's FAQ about calendars: question about a new release of Sunbird (e.g. version 1.0) states, “The development of Sunbird has been discontinued and thus, we unfortunately won't release any new versions of it. If you are still using Sunbird, you might consider to switch to Lightning.” (Hyperlinks may have been modified and/or added to the quoted text.)

More option(s), using third party code
[#spicbird]: Spicebird by Synovel
Integrating functionality for calendar, E-Mail, and chat
Outlook
Modern versions of Microsoft's paid-for Outlook client may support calendars. Such support may be updated or replacement code of earlier offerings by Microsoft, such as the software described by Wikipedia's article on Microsoft Schedule+.
Scalix
The Wikipedia's article on Scalix says that “the modifications” to the MPL to create the SPL “have not been approved by the Open Source Initiative” (“OSI”).
StarSchedule
This software is now listed in Wikipedia's Article on StarOffice: section listing “Older discontinued components”.
[#apleical]: Apple's iCal

This may be unrelated to ical, a Unix program described by Wikipedia's page ical.

[#objchart]: “Object/vector editor”/Diagramming/flowchart software
OpenOffice Draw
...
Dia
Dia is a package suggestion from Debian's package of GNOME Office.
Kivio, Kugar, KChart
Part of the KOffice office suite (for KDE/Linux, and more recently also for Microsoft Windows and Mac OS X).
Some other altneratives
Open Source Alternatives to Microsoft Visio also lists ArgoUML and StarUML.
Visio
Visio Viewers
See TOOGAM's Software Archive of programs that work with common Office data
Visio Trial Software
Visio 2003 Trial Software (via shorter URL)
Misc office software categories
Mathematical forumlas
[#oomath]: OpenOffice Math
...
[#kformula]: KFormula
Part of the KOffice office suite (for KDE/Linux, and more recently also for Microsoft Windows and Mac OS X).
[#gfxedofc]: Graphics Editing (related to office suites)

Although there is quite a bit of graphics editing software available, and many office suites do not contain a dedicated program just for editing graphics, some do. Therefore, here is a list of some graphics editing programs which are often either related to, and/or used with, office software suites.

(Note: additional graphical editing options are mentioned in the more generalized graphics editing section.)

Raster graphics editing
GIMP
Perhaps listed here (in the section of Office software) most notably because of its mention on Wikipedia's web page on Krita: section about the software's history.
LICEcap
LICEcap records screen and creates animated GIF files. For Microsoft Windows and OSX, GPLv2.
Vector drawing editing
Inkscape
Inkscape is a package suggestion from Debian's package of GNOME Office.
Functionality of Microsoft Word

Many people may be unaware of this functionality built into Microsoft Word.

Rendering 3D environments
Blender

This software allows a computer to keep track of a 3D environment, which may then be rendered. (At least the original public releases of Blender were initially designed for rendering the 3D environment onto a 2D video output display. This was likely mainly because of one simple reason: electronic 3D visual output methods had not been mainstream when Blender was initially released.

One thing that has helped people be more familiar with Blender are its movies. Wikipedia's article on Blender: section about “Use in the media industry” lists such movies. Blender Open Projects might be the official home page for such projects. “Big Buck Bunny” was aimed to be humurous, while Sintel should probably be fully viewed by adults before being shown to young children. Some of the lines include “This blade has a dark past. It has shed much innocent blood.” Sintel is not a movie that lacks violent imagery.

Blender started out not being open source, but when the company that owned Blender was going out of business, an agreement was made with the business's creditors. The company promised to sell the software, so that it may be released freely to the open source software community, for the price of 100,000 Euros. (Wikipedia's page on the Blender software: “History” section indicates that 100,000 Euros was worth $100,670 USD, at the time.) Donations were sought and obtained: Blender.org's page on Blender Foundation's History notes, “To everyone's shock and surprise the campaign reached the 100,000 EUR goal in only seven” weeks.

Unsorted
[#oodraw]: OpenOffice Draw
OpenOffice.org page on Draw
Krita, Karbon14
Part of the KOffice office suite (for KDE/Linux, and more recently also for Microsoft Windows and Mac OS X). Wikipedia's page on Krita: section about the software's history mentions some names of this software before the “public release”: “KImage Shop”, “KImageShop”, and “Krayon”.
[#gfxview]: Graphics Viewing

Many programs that edit graphics (particularly those that have a graphical interface) can effectively be used to view graphics. The most popular graphics editors may be web browsers.

In addition to those options, there may be some programs that are specifically designed to view graphics. These programs are often smaller, and may contain features such as displaying a “slideshow”, by showing one image for a short preset amount of time and then moving on to show another image. (Other classifications of programs that may be used to show one image after another may be office presentation/slideshow software, especially the office presentation/slideshow software: section on web-based solutions, and some (a hyperlink to a specialized section would be nice...) screensavers.)

Project Management
Wikipedia's comparison of project management software, Wikipedia's article on project management software, and perhaps the following may have some relevance: Wikipedia's page comparing Time Tracking software, Wikipedia's page comparing Colloboration software, Wikipedia's article comparing issue-tracking systems
KPlato
Part of the KOffice office suite (for KDE/Linux, and more recently also for Microsoft Windows and Mac OS X).
Planner
Planner is a package suggestion from Debian's package of GNOME Office.
Others/misc
Scanner
XSane
XSane is a package suggestion from Debian's package of GNOME Office.
MS Office OCR support
Other apps/functions
...
Financial Software
[#bookkpng]/[#acctngsw]: Bookkeeping/Accounting
Bookkeeping/accounting software may help monitor money flow, work with printers to print checks. GnuCash, HomeBank.free.fr's HomeBank, PostBooks, xTuple, MYOB products, Intuit's original product, Quicken, which is aimed more for individuals, and Intuit's newer, higher end product, Quickbooks, Converting data, Microsoft Money, Sage software (e.g. Sage MIP and other Sage Products, Wikipedia's info on Sage: Competitors)
Taxes
Websites
Software
TurboTax
Payroll
Payroll processing
Time clocks
Software can perform a modern-day equivilent of having people punch time cards. Such software may act as a user interface. Presumably there will be a desire (and hopefully an implementation to fulfill the desire) to take the data from such software, and have that data be able to be used by other software, like the Payroll processing software.
Spreadsheets
See the Office Data section.
Point of Sale systems
See also: Further research needed: May modify inventory and/or provide Customer Relationship Management features?
Customer Relationship Management (Right term?)/Enterprise Resource Planning
CRM (e.g. SugarCRM, Microsoft Dynamics CRM, “Sage ACT!”)
Inventory
Inventory control, shipping software that prints shipping labels, websites that track shipments, etc.
[#gfxedit]: Graphics editing

This section is not extensive. Perhaps see NetPbm documentation: other graphics software (which lists many options for Unix), graphics editing with Office (suite) programs, image editing for additional options.

Netpbm

Netpbm is open source (free) software

Netpbm Program Directory lists programs, and has hyperlinks to manual files for each of the programs. Other details are available from additional Netpbm documentation.

Example conversion

As an example for converting a *.BMP file, use Netpbm's anytopnm or bmptopnm and then pnmtopng or pamrgbatopng program. First, grab the program: Getting Netpbm (instructions) indicates some options for various platforms, including Microsoft Windows users going to GNUWin32 page related to NetPbm for Windows which offers NetPbm for Windows (installer executable file).

bmptopnm -plain -verbose filename.bmp >> temp.pnm
echo Unix Results=$? DOS Results = %?
pnmtopng -plain -verbose -compression=9 -comp_mem_level=1 -comp_window_bigt=15 temp.pnm >> output.png
echo Unix Results=$? DOS Results = %?
Graphics conversion

See Netpbm, methods of shrinking PNG files, TOOGAM's Multimedia page: Multimedia file converters.

[#pngshrnk]

It may be possible to use lossy compression with some software that supports PNG. Fortunately, most software that supports PNG will default to using lossless compression.

In at least one test, AdvanceCOMP made a PNG file that other programs was not able to be further reduced by several other optimizers.

Disabling auto-conversion

Apple's auto conversion

AdvanceCOMP
advpng -z4 filename.png

AdvanceCOMP home page, AdvanceComp with advpngidat

PNGOUT

Made by Ken Silverman, who also made KZip and has worked on 3D engines (complemented by rival John Carmack)

pngout input.png output.png

A graphical interface may be available at PNGOUTWin.com.

OptiPNG

PNGCrush's home page refers to this as “fork of pngcrush development” which is “by Cosmin Truta, with a slightly different feature set and search space.”

optipng -o 7 -k filename.png
PNGCrush
pngcrush -brute -cc -e png -fix -l 9 -reduce -rem alla-v -w 512 filename.png

If the output file is unsupported by some software, try removing -cc and -rem alla

GNUWin32 PngUtils for Windows contains several PNG-related tools. Trimage is available for Linux operating systems. ImageOptim is similar (and was the inspiration for Trimage) for Mac.

More editing options
MyPaint

Some reviews indicated that the interface of this GPLv2 “open source” software is rather simplistic.

MyPaint.org Downloads provides info.

Paint.NET

This software's domain is getpaint.net

Wikipedia's article for the Paint.NET software (September 6, 2016 archive) (“Overview” section) noted the history involving various open source licensing.

[#entrtain]: Entertainment Software
[#games]: Games
Board games (and variants)
[#scrnsavr]: Screensavers

On a related note, blanking the screen (possibly in a way that saves electricity) is described in the section about lowering power consumption.

Because of the high number of systems that run custom screensavers that are eye-catching mostly just to be interesting, much of the information is placed in the entertainment section of information.

[#wwwsoft]: World Wide Web software
[#wwwbrows]: Web browsers

For some archives of older versions of web browsers, see Browsers.Evolt.org, the just-mentioned websites (OldVersion.com and FileHippo.com), and for some older software, TOOGAM's Software Archive of Web Browsers/Clients.

[#wgfxplugs]: Web Add-ons

There may be various terms for this sort of software, such as Add-ons, or plug-ins.

For some of the most popular add-ons, see the mozdev PluginDoc: Windows (Most Popular) page. TOOGAM's web page about graphical browsers: Web Plugins for the graphical browsers may also point to some add-ons.

Web development/editing
Quanta Plus
Quanta Plus was listed as software number five on the front page of osalt.com. (That's not saying that Quanta Plus was #5 in just a list of web page editors. This is saying that Quanta Plus was the #5 piece of software at all, when competing against software from all different software categories.)
KompoZer
...
IceApe / SeaMonkey

Modern versions are basically variations of Mozilla Firefox with additional features including a built-in a web editor named “Composer”. (Older versions were basically versions of Netscape Communicator with a built-in web editor named “Composer”.) E-Mail may also be supported in SeaMonkey (which it is believed was also part of Netscape Communicator, but not Firefox nor Netscape Naviator). This SeaMonkey software had been distributed by Mozilla, although after version 1.7.13 the software has been controlled by a new group named the “SeaMonkey Council”.

Amaya

An Open source web editor by W3C, the organization responsible for HTML standards. (W3C was founded by Sir Timothy John Berners-Lee, who produced the first client and server for the world wide web.) This software is known to focus more on correct implementation of standards, rather than trying to focus on a spectacular end user experience. (The web browser is not designed with a focus on features like supporting poorly formatted HTML code. Such a feature is simply not the intended purpose/focus for this specific software.)

Looking for yet more? See: TOOGAM's Software Archive: web editors.

For other web-related software, see software powered by Mozilla.