Definition - What does Back Button mean?
Techopedia explains Back Button
A back button also represents the principle of successive pages as a key Web design component. This is a technology principle utilized by many areas of IT, such as Apple's early HyperCard program. In these and similar technologies, a complete application is developed and presented to end users as a set of pages or cards, and a back button that is used a critical navigation tool.
It is likely that the back button will continue to be a popular device and application control, as most end users are familiar with the concept of linked pages.