Serialization is the process of converting an object into a string (text) that can be stored for reuse. Serialization stores both data members and member functions into strings, which can be stored in text files and databases or passed to other scripts. This is useful for storing or passing PHP values around without losing their type and structure.

To serialize an object, you pass an object name to the serialize() function. You can also reverse the process using the unserialize() function. The unserialize() converts the serialized string back into a PHP object.