Fleas are insects whose mouthparts are specialized for piercing skin and sucking blood. They are dark-colored, with long legs specialized for jumping. Ordinary flea can jump for up to 13 inches so it is quite easy for them to move and hide.
The greatest problem with fleas is that not only do they attack a wide variety of animals like dogs, cats, chickens, rabbits, squirrels, mice and others, but they attack humans too. Regardless of the fact that some fleas specialize as parasites on individual animal species (like cat fleas or dog fleas), they have no problem with using other species as a host (well... like you and me).
Flea bites cause itching, but fleas are not just a source of annoyance. Their saliva can cause allergic reactions and in some extreme cases, fleas can cause anemia. The fleas are quite dangerous pests since they can also transmit many viral and bacterial diseases to humans as well as pets and other animals.
Since fleas can settle in your hair in less than 10 minutes, as soon as you notice an infestation, you should react and do your best to kill all the fleas. You must take three actions to solve flea infestation. You must kill fleas on your pet, you must kill fleas in your home and you must prevent flea re-infestation.