What is trapped or stopped by the filter?

A filter is designed to trap or stop unwanted particles, impurities, or pollutants from passing through. This can include dust, allergens, bacteria, viruses, and larger debris in air or water filters. In specific applications, such as oil filters, it can also capture contaminants like dirt and metal particles. Overall, filters help maintain the cleanliness and quality of fluids or air by removing harmful substances.