Source control is a necessity when building more complex applications, whether using ServiceNow or not. They bring great advantages, including a mechanism of sharing code between many developers, having multiple versions that can quickly be switched between, and tracking the history of changes.
ServiceNow introduced the concept of Team Development in the Dublin release of ServiceNow. This brought some Git-style concepts to ServiceNow, including comparing instances and pushing and pulling record versions between instances. However, the Helsinki version of ServiceNow supports Git repositories directly, letting you store applications in either your own repository or a public service such as GitHub.