Methods in the Web API can change over time, however, despite this, it's important that such a change does not break older implementations. In order to be able to do so, Web API 3 uses query string versioning.
In order to specify a version, you simply have to add another query string parameter, v for example, v=1. By default, the version is number is always 1, so if you want to get the newest version, you have to change it explicitly.
Web API methods are updated as follows: