Pinout

The RMA started its standardization in 1934, collecting and correlating tube data for registration at what was to become the Electronic Industries Alliance (EIA) which now has many sectors reporting to it and sets what is known as EIA standards where all registered pinouts and registered jacks can be found.

Therefore, pinouts are a vital reference when building and testing connectors, cables, and adapters.

Many connectors have multiple standard pinouts in use for different manufacturers or applications.

[1] While one usage of the word pin is to refer to electrical contacts of, specifically, the male gender, its usage in pinout does not imply gender: the contact-to-function cross-reference for a connector that has only female socket contacts is still called a pinout.

Viewed from the front (outside) of Female Type A USB receptacle:

A pinout diagram of a very common 555 timer integrated circuit showing its eight pins (numbered 1-8) and their corresponding functions ("ground", "trigger", "output", etc.)
PS/2 connector pinout
4017 pinout
4017 pinout