Time-travel debugging, also known as reverse debugging, allows developers to step backward as well as forward in their code execution. This is a powerful tool for debugging production code because it enables developers to see what happened at any point in the program's history. The technique was first introduced with Smalltalk-76 and has since been implemented in various languages, platforms, and IDEs. There are three main approaches to implementing time-travel debugging: record & replay, snapshotting, and instrumentation. While running traditional debuggers doesn't make sense in production, time-travel debuggers can record a process execution on one machine and replay it on another machine for debugging purposes. This technique is particularly useful when dealing with hard-to-repro bugs or when recording the execution of a program is already part of its normal operation.