A sequence diagram simply depicts interaction between objects in a sequential order i.e. the order in which these interactions take place. We can also use the terms event diagrams or event scenarios to refer to a sequence diagram. Sequence diagrams describe how and in what order the objects in a system function. These diagrams are widely used by businessmen and software developers to document and understand requirements for new and existing systems.
![](https://teksoftclub.wordpress.com/wp-content/uploads/2019/10/uml-sequence.png?w=709&h=408&crop=1)