Every Region has a fade-in and fade-out. By default, the region fade
+is very short, and serves to de-click the transitions at the start and
+end of the region. By adjusting the regions fade length, a more
+gradual transition can be accomplished.
Region fades are possible at the beginning and end of all audio regions. In Object Mode a grip appears at the top left and top right of an audio region when the cursor hovers over it. Placing the cursor over the top of the grip displays the region fade cursor tip. Click and drag the grip left or right in the timeline to adjust the length of the fade.
To activate/deactivate or change the "style" of the Region fade, hover the cursor over the regionfade grip till the cursor tip indicates region fade editing and context-click (right-click) to bring up a context menu. In the context menu there is a list of options for the regionfade. Activate/Deactivate enables and disables the regionfade. The different types of fades are, Liner, Slow, Fast, Symmetric and Constant Power
Region fades are possible at the beginning and end of
+all audio regions. In object mode, a grip appears at the top left and
+top right of an audio region when the cursor hovers over it. Placing
+the cursor over the top of the grip displays the region fade cursor
+tip. Click and drag the grip left or right in the timeline to
+adjust the length of the fade.
+
Crossfades refer to the behavior of a region fade when regions overlaps another region. Crossfades are regionfades. When one region overlaps another and there is a regionfade on the top region the fade-out will be mirrored as a fade-in on the underlying region. The grip for the top region will allow changing the length and type of the crossfade.
Crossfades refer to the behavior when you want to make
+a smooth transition (mix) from one audio region to another on the same
+track. Historically, this was done by splicing 2 pieces of analog
+tape together, and this concept was carried forward into digital
+editing. Each track is a sequence of sound files (regions). If
+two regions are butted against each other, there needs to be a method
+to splice them smoothly together. The crossfade allows one region
+to fade smoothly out, while the next region fades smoothly in, like 2
+pieces of tape that have been cut at and angle, and overlapped.
+
But Ardour uses a more refined "layered" editing model, and
+therefore it is possible for multiple regions to be stacked on a single
+location with arbitrary overlaps between different layers. For
+this reason, crossfades must be implemented differently. We can't
+assume that a crossfade is an entitry that exists between 2 regions;
+instead each region must have its own associated crossfades at each
+end, and the topmost region must always crossfade down to the
+underlying region(s), if any.
+
Ardour solves this problem by putting a crossfade at the beginning
+and end of every region. The fades of the bottom-most region are
+first rendered, and then each region is rendered on top of the one
+below it, with fades at the end of each region providing a crossfade to
+the region(s) beneath it.
+
It is important to understand that region fades are crossfades. When one region has
+another region or multiple regions beneath its fade area, then you will
+hear the topmost region fade-out be mirrored as a fade-in on the
+underlying region(s). The grip for the topmost region will allow
+changing the length and type of the crossfade into the underlying
+region(s). In this way you can create a complicated series of
+crossfades, and then layer another region atop the others, and fade
+into _that_ complicated series. An image here would
+probably help.
+
If a region doesn't have any region(s) under it, then the region is
+crossfaded to silence; for convenience we call this a "fade"
+rather than a crossfade.
+
To activate/deactivate or change the shape of a region's fadein or
+fade-out, hover the cursor over the regionfade grip till the cursor tip
+indicates region fade editing and context-click to bring up a context
+menu. In the context menu there is a list of options for the
+regionfade. Activate/Deactivate enables and
+disables the regionfade.
+
Because each fade is also a crossfade, it has an inverse fade shape
+for the audio beneath the fade. It is important to know how the
+shapes differ, and which are most suitable for various editing tasks.
+
The different types of fades are:
+
Although these fade shapes serve specific purposes, you might find that
+any of the shapes is usable in your situation. The final decision
+is an artistic choice rather than a
These fade curves are developed to provide a range of common uses, and
+are developed with the least possible amount of changes in the "slope"
+of the line. This provides artifact-free crossfades. Some
+DAWs provide complicated fade editors with parametric "spline" controls
+of the fade curves. While it might be interesting to develop a
+fade curve with a faster cutoff, the mathematical difference between
+this and simply shortening the fade is vanishingly small; and the
+amount of effort to shorten the fade is much easier than messing with a
+crossfade editor dialog.