In PHP, the complex data can not be transported or can not be stored. If you want to execute continuously a complex set of data beyond a single script then this serialize() and unserialize() functions are handy to deal with those complex data structures. The serialize() function is just given a compatible shape to a complex data structure that the PHP can handle that data after that you can reverse the work by using the unserialize() function.
Most often, we need to store a complex array in the database or in a file from PHP. Some of us might have surely searched for some built-in function to accomplish this task. Complex arrays are arrays with elements of more than one data-types or array. But, we already have a handy solution to handle this situation.
Serialize() Function: The serialize() is an inbuilt function PHP that is used to serialize the given array. The serialize() function accepts a single parameter which is the data we want to serialize and returns a serialized string.
Unserialize() Function: The unserialize() is an inbuilt function php that is used to unserialize the given serialized array to get back to the original value of the complex array, $myvar.
Note: For more depth knowledge you can check PHP | Serializing Data article.