Significant features of Sequence Diagram

Sequence diagram is a dynamic model that represents the instances of classes and messages between them. It is very significant diagram among all behavioral diagrams because of various significant features or aspects of the sequence diagrams. Objects are represented horizontally at the top of the sequence diagram. Dotted lines called lifeline vertically below it. Focus of the control is a thin rectangle placed over the lifeline to represents the flow of messages. Message is a communication between the objects shown by arrow connecting towards the direction of message that is being passed. Sent message represented as solid arrow line whereas reply messages with dotted arrow line.
To create a sequence diagram, there are some steps to follow.

Identify Objects: the objects that are going to interact with other elements of the system in the use case sequence to be identified first. Which needed more focus on essential information that is need to capture by the system. Generally, objects can be taken from the use case reports. Source and destination of the use case is better start to identify the object. Classes could be external actors of the system represented on the use case diagram.

Adding Messages: to represents the messages between the objects can be shown by drawing arrows pointing towards the direction of transmission. Time sequence includes the sequence of arrows between the objects from first to the last. Parenthesis used next to the message name to represents the parameters if any passed along with the messages. If message is expected to be returned as response represented by drawing dotted arrow line.

Placing Lifeline: Vertical dotted line should be drawn below to represents the existence of the object during the sequence. Temporary object ‘X’ should be placed at the end of the lifeline to convey that the object is no longer needed to the system. By drawing rectangular box over the lifeline to represent the sent and received messages of the object in a sequence.
Sequence diagram became popular because of its significant features and efficient way of creation.