You must be thinking which is better, I'll help you out in some simple steps. Stay tuned.

Centralised exchanges:

Some of them are Binance, KuCoin, OEX, Kraken, Coinbase, Bityard to name a few.

There are few cons here:

• You need to submit your Identity, documents to avail full services.
• They can freeze your funds if found sus.
• High withdrawal fees

So basically you have no authority over your coins, but there are some pros here.

• Very low risk of scamming out of your bag if you are new to the hood.
• Ease of access
• Early access to ICOs.
• It is mostly secure and you can withdraw Fiat easily.

Now let's head to Decentralized exchanges :

The pros are:

• Your keys, your coins
• Vast number of coins are available for trading
• Low withdrawal fee
• High APY in the pools
• No need of your Identity, totally anonymous.
• Great Applications are available for maximum profits.

Here are some cons:

• Large number of scam coins.
• If you don't know what are you doing, there is a chance of losing money.
• Less secure.
• If you lose your seed phrase or give it out, you're screwed.
• Gas fees, if you are using Eth chain.

So if you are relatively new to cryto, use a Centralised exchange. Otherwise go for a decentralized one if you are comfortable.