[#guid]: “Globally-unique” identifier

In theory, a GUID is a number that is globally unique.

In reality, identifiers that are commonly called a “GUID” are often assigned in a de-centralized manner, and so there is no real way to guarantee that they are definitely globally unique. In such cases, the chances of another computer using the same globally unique-ish identifier are not necessarily impossible. However, problems from GUID collision is considered to be statistically extremely unlikely. (Even if two computers in the world do use the same identifier, this isn't likely to be a problem if the GUID is contained enough that the data from each of these computer never ends up being seen by the same computer.)

[#gpu]: Graphical Processor Unit

A chip specially designed to produce calculations that enable high performance by circuitry that is dedicated to producing video output. The chip may, in theory, be used for other purposes. Perhaps a chief example of this would be using the stream processing of GPUs to brute-force attack a challenge to locate desired Secure Hash Algorithm (SHA) keys. This process is performed by the math behind the “distributed computing” task of mining Bitcoins, and the circuitry used by the stream processing of GPUs made by AMD's ATI have been found to be designed in a way that facilitates these calculations. However, most commonly these chips are simply used for outputing video.

[#guidline]: guideline
Administrative term: guideline

Basically, this is a recommendation. People may generally feel free to not follow a guideline whenever they determine that a situation calls for a better/different approach.

(This is a term that gets contrasted to other administrative terms like policies, procedures, processes, or standards.)