[#partiton]: partition

The term quite literally means “barrier”.

disk partition

A segment of disk storage capacity. Often a partition is dedicated to store a filesystem volume. Since the process of creating a filesystem volume will often use every bit of space available on a disk or partition, smaller volumes can be created by splitting the disk into smaller segments.

Generally, the term “partition” means a segment of a disk. However, a BSDlabel/disklabel “partition” may refer to a segment of a disk which exists entirely within another partition such as an MBR-style partition. In environments (such as BSD operating systems on x86 platforms) where such ambiguity exists, it is a great idea to try to explicitly clarify which sort of partition is meant when using the term “partition”. (This may be discussed further by different types of partition terminology.)

A “partition scheme” generally refers to how partitions are laid out on a disk. This will include the size of the partition, and where each partition starts. Other details about partitions, such as the value of a “type” identifier, might also be considered to be part of the partition scheme for that disk.

More details, about creating a partition scheme/layout on a disk, are available in the section about disk layouts.

cubicle partition
A “partitioning wall” (or “partition wall”) piece may be a segment of a wall that is about 1.75 meters tall. (There is roughly 4 to 5 feet, using “customary” measurements.) They are often approximately as wide as they are tall, giving them a rather square shape. Multiple of these pieces may be attached, creating walls that are relatively easy to move if there's a desire to do so. They often have a cloth surface, and may have a plexiglass window so a portion of them may be seen through. This is commonly used to allow a large area (room) in a building to be inexpensively segmented, so individual staff members may have an area to work that is seperated from other workers. In addition to providing a small sense of individual space (compared to if there were no cubicle walls), they often serve to help reduce how much sound spreads, such as the voices of people who are talking into a telephone (and not necessarily desiring that other people, especially other telephones, end up hearing the sound).
[#patabbr]: PAT
See: port address translation
PC
Personal computer. This may generically be used to refer to the platform of computers compatible with an IBM PC, including 32-bit x86 computers. The term has also been used to refer to x86-compatible platforms, including 64-bit computers which are largely compatible with 32-bit x86 applications even though 64-bit systems may not be as compatible with the 16-bit IBM PC. The term may also be used to reference an x86-compatible workstation, contrasting such a computer to upper-end server-class hardware, since the technology of many common workstations is technology fundamentally similar to personal computers.
[#periphrl]: peripheral

A peripheral device generally refers to an add-on device that may be less critical for basic computer operation. In the days when MS-DOS was the most common OS being used on a generic-brand PC, the term “peripheral device” could include speakers, microphones, and even a mouse, while the monitor would be considered a key part of the base system. This was before mice started to be commonly used for a large variety of tasks.

Some older text books correctly identified the term “peripheral” as generally being an abbreviation referring to the longer phrase “peripheral device” or a “peripheral card”. A sound card, for example, was generally considered to be a luxary add-on. (Since then, sound cards started to get to be built into motherboards. So whether a specific type of device is considered to be peripheral may change over time.)

The term may still refer to concepts of being less necessary, or being on the “outside” edge.

(In life, beyond the realm of computers, the term is probably most commonly used when referring to “peripheral vision”.)

[#pid]: PID (“process ID”)

A number that is assigned whenever a software program is started. The number is unique to the computer, so every program running on the computer will have its own unique PID. If there are multiple copies of the program running, then the program has started multiple times, and each copy received a PID when it was started.

Note that multiple programs may simply be individual pieces of another, larger program. In other words, a (larger) program may have multiple pieces, and these pieces may be separate individual programs. In this case, each piece may be considered to be a separate process, so there may be multiple PIDs when a user starts up a single program.

(Another term related to this concept of PID: PPID.)

[#pixel]: pixel
This is said to be an abbreviation for “picture element”. Many people understand the pixel to be the smallest unit that a monitor can display. This can be confusing when people then try to learn about parts of monitors (especially CRT monitors) such as phosphors and shadow masks, and hear about different sized pixels. To be clear, a pixel may not be the smallest element: a pixel may be made up of a group of phosphors. However, the pixel is the smallest element which can be uniquely identified by hardware such as the video card, and by software which controls that hardware. An individual monitor may implement each pixel by combining multiple small phosphors that are affected by the electrons that the monitor is using. The amount of phosphors used per pixel (which would affect the actual size of the pixel) may vary between monitors and be affected by things like the video screen resolution, but this isn't something that is available to the video card or any other circuitry in the computer or any software that is using that circuitry.
[#pointdvc]: pointing device

See: rodent.

[#policy]:
Technical term: policy

This may refer to settings that are designed to help rules be automatically enforced. One example is Microsoft Windows having “local policy”. Perhaps even more famous is the “group policy” functionality of Microsoft Windows, which basically involves client machines asking a server for policy settings and then using those settings to affect the “local policy” settings.

SearchSecurity TechTarget: Differentiating between policies, standards, procedures and technical controls seems to identify this concept with the term “technical control”. A control is used to help enforce the rules of administration's policies.

[#polcyrul]: Administrative term: policy

The term “policy” may be distinct from some other terms, such as standard, procedures, and guidelines.

Basically, a policy refers to a set of rules about what is expected by administrators/management.

[#pop]: POP
Post Office Protocol

Most commonly implemented as POP3, this refers to a protocol that E-Mail clients have used to communicate with E-Mail servers to check for new mail. This is an older, and basically inferior, option to IMAP4 which provides end users with support for multiple E-Mail folders. However, POP3 is a bit simpler in some ways, and so may be an easier protocol for a software programmer to start implementing.

Point-of-Presence

A term quite often used when discussing a telecommunications company. This location provides services to additional organizations. A demarc point may be directly connected to the POP, or might even be located at the POP. (The common location for a point of demarcation may vary in different locations, such as different nations.)

[#port]: port
A hardware port
A connector that a plug gets placed into. Also known as a “jack”.
Software ports

Software designed for one platform may be “ported”, which means that support is then provided for a different platform. The resulting software may be called a “port”.

For OpenBSD, the term “port” may refer to a software program/collection. Specifically, the term “port” refers to the collection of files needed to make a release of the software, so the software's source code is certainly part of the port. (The term “package” is a specific term in OpenBSD jargon, and refers to compiled software that was created using the port.)

Hardware platform
NetBSD's introduction to ports says “a supported architecture” (a.k.a. a platform of computer hardware) is called a “port”.
[#prtadrtr]: port address translation (“PAT”)

Port Address Translation. RFC 3022 (info about NAT) describes this as “Network Address Port Translation, or NAPT”, although it is often referred to as “Port Address Translation (PAT)” (as can be seen by RFC 4925 section 2.3).

Commonly, this involves a firewall allowing outgoing traffic. The traffic is then modified so that the “source” IP address will be translated, probably most commonly made to appear like the traffic is coming from the device that is going the translation. The device that performed the translation also keeps track of where it received the traffic from, probably by storing this information in a section of memory that may be called a “table”. Then, reply traffic will go to the device that performed the translation. The device that performed the translation can then look in its memory to see where the reply traffic should be forwarded to.

[#pots]: POTS

“Plain ol' telephone service” refers to using standard landline phone service, without the broadband data speeds offered by newer technologies such as ISDN or newer (notably DSL). This service was able to provide the needed technology for voice communications, dial-up modems, and fax machines. Regulatory limits to electrical output power were blamed for preventing modems from getting faster than about 56kbps when POTS was used, which led to demand for new services that could provide faster data rates. Telecommunications companies were able to offer these services for higher prices than just standard phone service.

Related details may be found at: Glossary for PSTN, POTS Modem, download POTS speed increases.

[#ppid]: PPID

Parent Process ID. This is the PID of a parent process. When a “process” (a running program) runs another program, the first program may be called a “parent”. Each program may be assigned a PID (“process ID”). The PID of the parent process may be referred to as the PPID of the child process.

[#procedur]: procedure

A set of steps.

Programming term: procedure

To get a definition for, and to compare, the terms procedure, function, routine, method, and program, see: Functions/Procedures/Methods/Routines.

Administrative term: procedure

In contrast to other terms (like procedures, standards, and guidelines), the term “procedure” may refer to a series of steps. For example, a document that describes how to tell a computer to shut down “cleanly” could be a procedure. This is not really a series of expectations (like a policy or a standard), but rather, is more of a technical how-to document. A procedure describes how to accomplish a task.

For example, a procedure might specify some directions on how to quickly obtain the information needed to create a report. This is different than a standard, which might specify how much detail is required for the result to be considered “sufficient” quality. This is also different from a policy, which specifies what is actually expected.

[#process]: process
running process

At least sometimes, this term refers to the concept of a running instance of a program. If an operating system runs a text editing program, that is a process. If the user then starts up a second copy of the text editing program in a multitasking operating system, then the second copy of the same program is another process.

This term was used heavily in Unix environments, where the ps command was used to show “process information” (info about one or more processes). Microsoft Windows has started to have some software that can show a unique “Process ID” number that gets assigned to each process, so the term has also become more relevant for administrators of Microsoft Windows machines.

set of procedural steps
(e.g. in contrast to a policy/procedure)
protocol

The term “protocol” refers to a set of rules, or perhaps (in some cases) conventions. In the realm of diplomacy, diplomats may be expected to observe certain protocols so that they please, rather than offend, people from a different culture. In the realm of network communications, the term protocol is often referring to a certain set of standards that need to be followed. Devices that send information are expected to follow certain rules when assembling and transmitting groups of information, so that the receiver of the data can correctly interpret the information that has been sent. This includes situations where the direct receiver of the data may be some sort of network infrastructure (such as a router, or even a switch) which receives the data just for the purpose of then relaying the information to another device. To accomplish this, sending and receiving devices tend to follow commonly-accepted rules so that the data may be interpreted the same way. A collection of such rules (which are often very detailed, nitpicky rules) is often referred to as a “protocol”.

[#pdu]: protocol data unit (“PDU”)

The term PDU refers to a unit/group/bunch/collection of data that is used when devices communicate.

Most/all common protocols that operate on Layer 3 of the OSI Model (the “Network” layer) will use a PDU called a “packet”. Most/all common protocols that operate on Layer 2 of the OSI Model (the “Data Link” layer) will use a PDU called a “frame”.

The concepts behind a packet and a frame are the same, but using these different terms helps people to realize what layer of the OSI Model is being used. This way, when people talk about frames (even if discussing a relatively unfamiliar technology), other people can understand that the devices being used are likely processing MAC-48 addresses, are not paying attention to IP addresses, and that the unit of data is not likely to be routed to a different subnet. (Instead, if the payload of that data needs to be routed, a new frame will get created.) For these types of reasons, using the correct terminology is preferred.

[#ps2]: PS2

For people who play video game consoles, this may be an abbreviation for “Playstation 2”. Computer gamers will often be familiar with that abbreviation from video gaming jargon. The logo for the original “Playstation 2” gaming console looked like the three characters PS2, and the Playstation 2 Slimline was more well known as a PS2 Slimline or PS2 Slim.

PS2 may also be a misspelling of PS/2. For computer gamers, the term PS2 may cause some confusion from ambiguity caused by the homonymity with the term PS2.

[#persys2]: PS/2

The term PS/2 refers to the IBM Personal System/2 computers, which were newer than the PS/1 systems that were made by IBM.

The PS/2 computer systems included several new standards, such as VGA, but may be most well known for the PS/2 keyboard ports and the PS/2 mouse ports.

[#ps2port]: PS/2 ports

See: PS/2 ports.

For computer gamers, the phrase PS/2 may cause some confusion from ambiguity caused by the homonymity with the term PS2.

PSTN

“public switched telephone network”. This refers to telephone service provided by a landline/wired telephone company used by the general public. See: Communications hardware: POTS Modem for details related to PSTN (much of which may be details specific to using computer equipment with the PSTN). See also: POTS.

[#pupsftwr]: PUP

Officially, the term stands for “potentially unwanted program”, although in many cases the term “probably unwanted program” is just as accurate and more precise. This refers to software which is typically not desired to be used, but which is often run anyway, possibly as the result of being bundled with an installer that also installs other software. Some anti-malware software has been known to check for PUPs. The reason that such software is called a PUP is probably due to an effort by anti-malware software vendors to not get sued for defamation (negative statements), libel (inaccurate negative written statements), or slander (inaccurate negative spoken statements).