A priority encoder is a circuit or algorithm that compresses multiple binary inputs into a smaller number of outputs, similar to a simple encoder. The output of a priority encoder is the binary representation of the index of the most significant activated line. If two or more inputs to the priority encoder are active at the same time, the input having the highest priority will take precedence. Priority encoders can handle all possible input combinations, but at the cost of extra logic. Applications of priority encoders include their use in interrupt controllers (to allow some interrupt requests to have higher priority than others), decimal or binary encoding, and analog-to-digital / digital-to-analog conversion. Priority encoders can be easily connected in arrays to make larger encoders, such as one 16-to-4 encoder made from six 4-to-2 priority encoders. Priority encoders can be efficiently constructed by recursion.