What are client-side prepared statements?

Question

Trying to learn something new - specifically trying to choose wether to use MySQLi or PDO for future projects when working with MySQL - I stumbled upon this page which shows

Answer 1

With PDO, you can use prepared statements (in code) whether the database that you are connecting to with PDO supports them or not.

If the server handles prepared statements, then PDO will let the server handle them (server side). If not, then PDO simply emulates prepared statements within PDO (client side), but ends up having to send each query to the server.