What is this?
SDL (Simple DirectMedia Layer) is a cross-platform C library for writing multimedia software such as games and emulators.
Is this a library I link into my own app, or a program I run on its own?
A library: you link SDL into your own application and call its API from your code — it is not a standalone program.
How do I get it and start using it?
Grab the latest release, then follow INSTALL.md in the repo — it contains the installation instructions and a quick introduction.
Which platforms does it run on?
Per the repo metadata it targets Windows, macOS and Linux on desktop plus iOS and Android on mobile — one API across all of them.
Can I use SDL for anything besides games and emulators?
Yes — the README names games and emulators as examples ('such as'), not the limit. It targets multimedia software in general: anything that wants one portable media API across platforms.
Is the project still active?
Yes — the repo is not archived and runs GitHub Actions workflows for builds and releases (build.yml, release.yml), with around 16.8k stars.