TTL (pronounced ‘turtle’) stands for “Terse RDF Triple Language” and is a file format used to express RDF data—a common alternative to N-Triples, JSON-LD, and XML in the RDF space. The format .ttl is a W3C standard that is described as a “general-purpose language for representing information in the web”.
Representing RDF, .ttl files store facts as triples, and TriG is an extension of TTL that accepts quads (to utilise named graphs).
If I wanted to document the fact that I like turtles in a .ttl file, I could do so like this:
@prefix : <http://www.oxfordsemantic.tech/Turtle/> .
:crush a :turtle;
:eats :coral ;
:enjoys :swimming ;
:is :cool .