Like any other texture, you map a file texture to an attribute of a material (shader). You can map file textures as a tileable (repeating) image where the opposing edges of the texture line up.
Procedural textures are tileable by default, but if you want to tile (repeat) file textures, you must make sure edges match properly to prevent seams. To make sure edges match properly, you can use an image editing package to offset the image, then touch up light or dark areas in the offset tile.
A tileable bitmap image is one that can be broken down into smaller pieces. Tileable images load faster and easier by the renderer, saving valuable rendering time.
You can also use a single File texture node to load and preview or bake textures composed of multiple images that correspond to the grid tiles in your UV layout. For more information, see Loading multi-tiled UV textures through a single texture node.