You may have guessed it, but Gulp on its own does not do a lot (I am having deja vu here). You need plugins to get any serious work done. Luckily, Gulp has quite a lot of those. The initial idea was that any Gulp plugin takes some input and outputs the result as a Node.js Stream object. However, in practice, this is often not the case. Some plugins return nothing, some write their output to disk and return the original input, while some watch files and never return at all. That sounds bad, but it does not have to be. You have to take into account that a lot of plugins are simply wrappers around other programs that were not created to work with Gulp (or any task runner) at all. Just be sure you read the plugin's documentation and use it as it was intended. Luckily, Gulp can work around these issues quite well.