What does 'transient' mean in Java?

A class field marked with the keyword transient will not be serialized. This means its value is not saved when writing the object to a stream or file. Upon deserialization of such an object, the transient field will have the default value for its type (0 for numeric types, null for reference types, and false for boolean).

It is used, for example, for:

• Storing sensitive data that should not be saved.
• Fields that depend on the runtime environment and do not make sense upon deserialization.
• Cached or temporary data that can be recalculated.