Looking for DEX Help/Advice

I’ve been in the crypto space since 2017, but have only used CEXs (centralized exchanges – Coinbase, Kraken, Kucoin, Uphold) for purchasing and trading crypto. As we’ve all seen and know, these larger CEXs have trouble staying functional in the middle of run-ups, which is no good when you’re looking to make moves. Looking for information on DEXs (decentralized exchanges) – what they are, how they work, advice on how/when to use them, etc. Or if you have good resources for where to learn more. TYIA!