A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
Questions about the graphics driver — system software that controls a computer's video adapter (aka graphics card) or GPU.
the operating system's lock/login screen. It is handled by the LightDM display manager and known as "Pantheon Greeter" in elementary OS, though other greeters are available.
the GRand Unified Bootloader, a BootLoader that can be used to boot most operating systems.
Questions related to physical hardware, and how it interacts with elementary OS.
for any question about the images that represent applications. These images show up in Slingshot and Plank. Questions can be about duplicates, icon packs, low quality icons and more.
The effort to make software match a region's culture, mainly through translation to its language but also through adaption to its customs
Questions about using and connecting to the internet on elementary OS
Questions about the Java Development Kit (JDK) in relation to elementary OS
For questions concerning the elementary OS kernel (which is the same as Ubuntu's kernel), including compiling, and questions relating to modules
Questions about keyboards, both touch and otherwise. However, please add the "touchscreen" tag for touchscreen keyboard questions.
Questions about keyboard shortcuts: both which ones to use and how to create custom shortcuts.