Bedding is one of the most important elements of a small animal's habitat — it affects comfort, odour control, respiratory health, and in burrowing species like hamsters, the ability to perform natural behaviours. Paper-based bedding is the most versatile and widely recommended — it's absorbent, dust-free, and safe for virtually all small animal species. Aspen wood shavings are a good alternative. Avoid pine and cedar shavings — the aromatic oils are respiratory irritants and potentially hepatotoxic to small animals. For guinea pigs, fleece liners over an absorbent pad layer are increasingly popular — reusable, soft, and very comfortable for guinea pigs whose feet are susceptible to wire-bottom cage injuries.