1. When referring to a connection types, DIN is a connector that conforms to a standard defined by the DIN group. Computer keyboards, computer mice, network routers, video appliances, and Apple serial devices are a few examples of hardware devices that may use a DIN style of connector. Today, the keyboard 5 DIN connector has been replaced by the PS/2 and USB connectors.

5 pin DIN specification

Pin Voltage Assignment
1 +2.0 to +5.5v Keyboard Clock
2 +4.8 to +5.5v Keyboard Data
3 +2.0 to +5.5v Reserved
4 Ground Ground
5 +2.0 to +5.5v +5.0V DC

2. Short for Deutsche Institut fuer Normung, DIN is a German standardization group.

3. Shorthand for Do It Now, DIN is commonly used in chat rooms and online gaming. Below is an example of how this could be used in chat.

User1: You should really go visit that site.
User2: Don't worry I'll get to it sooner or later.
User1: DIN!!!
User2: Ok, ok!

Also see: Chat terms, Game terms, ISO