Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in three basic forms: woven (looks like mailbag sacking), needle punched (looks like felt), or heat bonded (looks like ironed felt). Geotextile composites have been introduced, and products such as geogrids and meshes have been developed.