This is an extension for Visual Studio Team Services.
It adds a task that allows you to make a smoke web test.
Find [here](https://en.wikipedia.org/wiki/Smoke_testing_(software) wikipedia's definition.
Basically it's a simple http request to make sure everything is working (or at least responding).
You can also use it to pre-load your system before going live.
Since the task is executed by the build agent, your build machines has to have access to the website you are trying to call.