Ticks are small parasites that feed on blood of vertebrates, attaching to their host and feeding slowly. They can go unnoticed for several days while feeding, as a result they become effective transmitter of a wide variety of pathogens in blood. Some human diseases transmitted by ticks include Rocky Mountain spotted fever and Lyme disease. Ticks are divided into two families: the hard ticks and the soft ticks. Hard ticks have shields on their backs and their heads are more tapered. Soft ticks have blunt heads and look like pieces of debris. Ticks can be carried inside homes by infected pets, or by hitchhiking on people or clothing. Ticks lay thousand of eggs and then die. It is important that tick infestation is properly treated, otherwise they will just persist.