Textured Backgrounds using Tiled Background Images

The image to the right is inserted as page content using the standard HTML img element.
Notice that it is on top of the background that gives a subtle pattern behind this section of the page.
It's dimensions are 100x100 pixels and its file size is just 13K.
You can see this graphic repeated over and over again in the footer to create a texture.

Tiling refers to a small graphic repeating, similar to how ceramic tiles on bathroom or kitchen floors repeat to create a larger pattern.
When a tiled graphic is constructed properly, you can't see the seams and it creates a textured background that looks continuous.
It is generally best to tile one small graphic to create a texture, thereby minimizing the page load time.
Larger graphics that cover whole areas of a page without tiling would generally be large and slow the page load.

A search for something like "textured background image" will yield many pages with free backgrounds suitable for making textures.