Cat fleas are the most common in the UK with bird and dog flea also being known to cause domestic problems.
All fleas are parasitic insects and require a host to feed upon and obtain its blood meal from. Generally of 1-4mm in length, fleas are not able to fly but can jump incredibly long distances due to their super strong and long legs. This action greatly assists the pest in jumping on to a host and hence why most humans will have flea bites from the knee area down.
Once mated, the adult flea will lay her eggs in the coat of the host and that of the surrounding environment (pet bed, carpet etc) These can lie dormant for a considerable length of time and once developed and supplied with a suitable stimuli such as heat or vibration will then hatch out.
A regular flea treatment programme for all pets is the best form of preventing an infestation along with regular thorough hoovering and hot washing of pet bedding will too assist.