Instead of loading one massive, unique image, software can tile a small, lightweight file infinitely, saving memory.

When a texture isn't seamless, repeating it creates obvious grid lines, mismatched edges, or jarring discontinuities. A seamless texture, however, creates an infinite, uniform surface, allowing you to cover any area without visible tiling.

Photoshop has a dedicated filter that handles the heavy lifting for simple textures.

Before you save, you must verify that the texture is truly seamless.