There are many types of different beddings used by owners all around the world. The most commonly used ones that can be easily found in Singapore would be the fleece, noodle mat and pee pad options.
Why is there a need for bedding in their cage? The answer is simple. It is not easy to potty train guinea pigs, which result in them peeing and pooping everywhere they want. It is then important to have bedding that is able to easily absorb pee while remaining dry on top.
Walking on wet surfaces all the time would most likely cause *bumblefoot on their feet, urine scalding on their skin or even cause respiratory infections from the intense ammonia smell surrounding them.
Beddings should be changed frequently to ensure that the above mentioned issues do not occur. Fleece and noodle mats should ideally be changed every 3-5 days while pee pads should ideally be switched out once or twice a day. These are all based on experiences and recommendations from fellow owners using the mentioned bedding options above.