Definition - What does Transient mean?
In computer programming, in Java specifically, transient is a keyword that is used to indicate that a variable should not be serialized. By default, all variables in an object can be serialized and therefore become persistent, but if a specific variable does not require persistence for any reason, the transient keyword can be used to mark that variable so that it is not serialized when the code is compiled.
Techopedia explains Transient
The transient keyword prevents a variable from becoming persistent. The latter means that a variable is turned into a stream of bytes and then stored in a file. This process is called serialization and is the default behavior for all variables in an object. Serialization is mostly relevant for network programming because an object that needs to be transmitted over a network needs to be converted into a series of bytes so that it can be sent in pieces; because of this every class and interface must be serializable by default. But if there is no requirement for network transport, the transient keyword can be used to mark a variable for exclusion when serialization takes place. This may save some computing resources and a tiny bit of processing time.