Fleas are small, wingless insects that belong to the order Siphonaptera. They are known for their ability to jump long distances relative to their size, which helps them move between hosts. Fleas feed on the blood of mammals and birds, making them common parasites on pets like dogs and cats. These pests can cause discomfort and irritation through their bites, leading to itching and allergic reactions in some animals and humans. Fleas can also transmit diseases and parasites, such as tapeworms, making it important to control infestations in homes and on pets.