Fades, crossfades and gain

Fades: drag the handles at the top corners of a selected or hovered audio region (a looped region’s fade-out is set from the menu or the Inspector), use the region menu’s Fade In and Fade Out submenus (None, 10 ms, 50 ms, 250 ms, 1 Beat, 1 Bar), or type lengths in the Inspector.

Inspector rows, as in Logic’s Region inspector:

Row	What it sets
Fade In	The fade-in length in ms. Click the label to choose Fade In or Speed Up.
Curve	The fade-in’s curve, -100 to 100.
Fade Out	The fade-out length in ms. Click the label to choose Fade Out or Slow Down.
Type	Out (a plain fade-out), or a crossfade with the following region: X (the two levels add up to unity), EqP (equal power, for material that isn’t the same on both sides) or X S (S-shaped).
Curve	The fade-out’s curve, -100 to 100 (also shapes an X crossfade).

Curves: 0 is a straight line. Positive values bow outwards (a fade-in rises quickly, a fade-out holds its level longer), negative values inwards. The default, 50, is the quarter sine every fade used before curves could be set, so older projects sound the same.
Speed Up and Slow Down change the playback speed over the fade, like a tape starting or stopping, following the curve; the level fades with it. The audio after a Speed Up and before a Slow Down plays where it always did. They are drawn with a dashed curve.
Crossfades: a crossfade type on a region whose end meets the next region on the track (touching or overlapping) crossfades the two over the Fade Out length, centred on the junction (or the middle of the overlap). Choosing a crossfade type for a region without a fade-out gives it the Crossfade Time (or the overlap). The next region’s own fade-in isn’t used meanwhile; its Fade In rows are dimmed. Followed by a gap, the type fades out like Out.
Region menu › Crossfade (Crossfade Time, None, 10 ms, 20 ms, 50 ms, 250 ms, 1 Beat) crossfades each selected audio region with the one that follows it, as EqP unless it already has a crossfade type; None removes it. It is greyed out when no selected region is followed directly.
Take folders and loops crossfade too. A take folder crossfades with its neighbours like any audio region, using the takes its comp plays at its ends. A looping region crossfades at its loop end, from its last repetition into the region that starts there.
Crossfade Loop Repetitions (region menu, for looping audio regions) crossfades each repetition into the next over the Crossfade Time (equal power), so a loop whose end doesn’t meet its start doesn’t click at every seam. Logic has no such option; it’s off by default.
Settings › Editing › Crossfade Time and Crossfade Curve (20 ms and 50 by default), as Logic’s settings of those names: the crossfades between takes in a take folder, the ones the X-Fade drag mode makes between regions that just touch (overlapping regions crossfade over the overlap), and the Crossfade menu’s first entry. The curve shapes take folder boundaries on both sides and the X crossfades the X-Fade mode makes.
A crossfade plays audio from the outgoing region’s file past its end and from the incoming one’s before its start. Where a file has none to spare, the crossfade slides and shortens to fit; where neither has any, the two regions fade out and in at the junction, over half the length each (a short dip rather than a click).
Crossfades are drawn across the junction: both regions’ curves, crossing. Drag the handle at the crossfade’s start (on the outgoing region) to lengthen or shorten it about its centre.
Playback, Bounce, Export, Bounce in Place, Freeze and Join all render fades and crossfades identically.
Anti-click fades: Settings › Editing › Anti-click Fades gives new recordings and imports short fades (0 ms by default).

Gain and reverse (audio regions)

Gain: region menu › Gain › +6, +3, +1, -1, -3, -6 dB, Reset to 0 dB, or Normalize (the loudest sample reaches 0 dBFS); or the Inspector’s Gain field. Gain ranges from -96 to +30 dB.
Gain handle: hovering over an audio region shows its gain in a small handle at the top centre of its name bar (on regions wide enough to hold it). Drag the handle up or down to change the gain, 0.25 dB a pixel, or 0.05 dB with Shift; the waveform grows and shrinks as you drag, and you hear the change while playing. Every selected audio region changes by the same number of dB from where it was (within -96, shown as −∞, to +30 dB). Double-click the handle to set them to 0 dB. A drag is one undo step.
Waveforms in the tracks area are drawn at their region’s gain.
Reverse writes a reversed copy of the audio to a new file, so the original stays intact.