what are the latches

latches are logic devices that latch onto or retain digital states (1 or 0) in data storage circuits. Because they use sequential logic, digital latches control and are controlled by other circuitry in a specific sequence that is determined by a control clock and enable/disenable control signals. Latches, which represent the simplest form of data storage, sometimes have an enable input that is used to control the latch, or to accept or ignore the input stage. Latch outputs respond immediately to changes at the input. Several types of digital latches are available. Data (D) and transparent D latches have a data input. S-R latches have either set (S) and reset (R) inputs, or set (S) and clear (C) inputs. Gate S-R latches have an enable input. Digital latches that contain an array of latches, each of which can be programmed, are also available.