PHP is able to automatically serialize most of its variables to strings - letting you save them into storage like $_SESSION. However, there are some tweaks you have to know to avoid exploding .php scripts and performance problems.

He gives some code snippets showing the serialization of variables and objects and points out a few things that can't be effectively serialized (like resources and closures). The mentions the "__sleep" and "__wakeup" magic methods for automatic class serialization and mentions the Serializable interface that comes built in to PHP.