This type of sensors is very basic, often represented by simple binary switches, and can determine whether or not a certain area of the robot is in contact with something or has hit an obstacle. While such sensors are extremely easy to implement and have a very low cost, their main disadvantage, compared to other types of sensors which can do readings from a certain distance, is that the robot must actually touch the targeted object, as implied by the name. This is a major disadvantage and can even be hazardous for the robot if it is capable of higher speeds, as it cannot stop the instant a contact is detected.