eBay is a great place to buy and sell items. Just like you would be careful in an offline marketplace, you need to be careful in an online marketplace like eBay too.
eBay has many safety processes in place to help you stay safe online. The most popular safety process is eBay's feedback system.
The eBay feedback System can help you decide whether you want to buy or sell items with another person on eBay. You can do this by viewing the person's eBay profile. Here you can read feedback that other people have given when buying items or selling items to the person in question. You can read about eBay's feedback system and other safety measures in more detail here.