Felt underlayment is a type of material used beneath flooring to provide cushioning and sound insulation. It is typically made from recycled fibers, such as felt or foam, and is designed to create a barrier between the subfloor and the finished floor. This helps to reduce noise, improve comfort, and protect the flooring from moisture. In addition to sound absorption, felt underlayment can also help to extend the life of the flooring by minimizing wear and tear. It is commonly used with various types of flooring, including laminate, engineered wood, and vinyl, making it a versatile choice for many home improvement projects.