The Mesh Warp Tool allows you to distort an image (or portion of an image) using a highly customizable grid comprising of nodes and lines.
A mesh warp can be applied as a non-destructive, live filter. It can be accessed via the Layer menu, from the New Live Filter Layer>Distort category. Its provides the same context toolbar settings as the Mesh Warp Tool.
The live filter allows the effect to be edited (or removed) at any time after its initial application, using all of the original image's pixel data.
In contrast, the Mesh Warp Tool can be reapplied but each time it uses the already warped image and so useful pixel data may have been lost.
The following settings can be adjusted from the context toolbar: