According to Wikipedia “In the visual arts, texture is the perceived surface quality of a work of art. It is an element of two-dimensional and three-dimensional design and is distinguished by its perceived visual and physical properties. Use of texture, along with other elements of design, can convey a variety of messages and emotions.”
Texture in the real world is how things feel, close your eyes and touch the things around you. The surfaces of a couch, a desk, a screen, they all differ. Smooth, rough, gritty, these words describe textures you can feel in the world. How do you describe things you feel with your eyes, the use of texture in your work is important, things will seem plain if you do not add texture. Solid colors have their uses too, but add some texture to bring your work to life.
Here are some links to resources to lean about texture.
If you want to find textures to use, here are a few places
Or just do a Google image search for textures; add a word or two to look for something in particular, like stone texture, or water textures.
Have fun and feel free to post a link to some unique work highlighting texture.