在数字电路理论中，时序逻辑电路是指电路任何时刻的稳态输出不仅取决于当前的输入，还与前一时刻输入形成的状态有关。这跟组合逻辑电路相反，组合逻辑的输出只会跟目前的输入成一种函数关系。换句话说，时序逻辑拥有保存组件（内存）来存储信息，而组合逻辑则没有。

从时序逻辑电路中，可以建出两种形式的有限状态机：

时序逻辑因此被用来建构某些形式的电脑的内存，延迟跟保存单元，以及有限状态自动机。大部分现实的电脑电路都是混用组合逻辑跟时序逻辑。

In digital circuit theory, sequential logic is a type of logic circuit whose output depends not only on the present value of its input signals but on the sequence of past inputs, the input history. This is in contrast to combinational logic, whose output is a function of only the present input. That is, sequential logic has state (memory) while combinational logic does not. Or, in other words, sequential logic is combinational logic with memory.