Crossfading between sound-files is a fairly common and intuitive notion, but crossfades on a smaller scale can be used for a variety of means: removing artefacts from recordings, 'grafting' the start of one sound onto the end of another, and so on. The possibilities inherent in a simple crossfade are not to be overlooked...

There are two parameters: A fade in shape and a fade out shape. You need to click on the shapes that best represents the sort of fade you require.