What it means
Normally, if you send a 50-page PDF to an AI, it has to read it from scratch every time you ask a question. Context Caching saves the processed version of that file. The next time you ask about it, the AI recalls it instantly without re-reading.
Why it matters
It saves huge amounts of money and time. If you are building an app where users ask questions about the same manual repeatedly, caching makes it 10x faster and cheaper.