How do you add a fade transition in After Effects?

To add a fade transition in After Effects, you can use the "Fade In" preset found within the Effects & Presets panel.

Steps:

1. Locate the Effects & Presets Panel: In After Effects, find the "Effects & Presets" panel. If it's not visible, go to Window > Effects & Presets.
2. Search for "Fade In": In the search bar of the "Effects & Presets" panel, type "Fade In".
3. Apply the Preset: You'll see options like "Fade In Layer". Drag this preset onto the layer you want to fade in. The "Fade In Layer" preset will fade the layer in for the entire duration of the layer. There may be other fade presets that offer variations for different types of fade effects. Experiment to find the one that best suits your needs.