Tiling

Makes the edges of the image wrap, so copies laid side by side join without a seam.

The model is asked to paint something whose left edge continues into its right and whose top continues into its bottom.That is worth having for backgrounds, fabrics, ground textures and anything else meant to repeat, and of no use for a picture you are only going to look at once. It constrains the composition, so it is not free.The examples show one render repeated nine times beside the tile on its own, because a seam only exists where one copy meets the next.
Sampling · Interactive explorer Tiling
Tiling Off
Tiling On
The same picture both ways 512 × 512

The edges end wherever the image happened to stop, so every join is a hard line.The edges are made to wrap, so the grain and the gaps run on across each join.

The single tile that was rendered, with this setting Off The tile on its own The single tile that was rendered, with this setting On The tile on its own

Fetching the example images.