Vignette also known as ‘light fall-off’ is a cool way to give your video that film look you always wanted. It is a process by which we darken the edges of the frame compared to the centre. Vignetting can be caused naturally using filters or lens hood or can be artificially added later in post-production.
To create a Vignette in Adobe After Effects, you can either use the built in Vignette preset or create it manually by adding and masking a back solid layer.
Take a look at this Quick Tip video on Creating a Vignette in After Effects.