The choice of substrate depends on your reptile's natural habitat and specific needs. Common options include reptile carpet/mats, coconut fibre, sand, paper littler, bark, butcher paper etc. Ensure that the substrate is safe, non-toxic, and easy to clean. Some reptiles have specific substrate requirements, so research your species to determine the best option. Adding a natural looking substrate that is right for your reptile provides them with enrichment and encourages natural foraging behaviours.