Understanding Activity Diagrams: A Visual Guide to System Process Modeling

The main purpose of an activity diagram is to model the flow of activities and actions within a system or process. It emphasizes the control flow, decision points, and the sequence of actions involved in achieving a particular goal. Activity diagrams are particularly useful for process modeling, behavior visualization, requirement analysis, process improvement, and communication among stakeholders.

The above UML activity diagram describes a process of displaying products from different websites -

1. Start
2. User Lists down the products.
3. Then adds the products to the cart.
4. The products are only added if a product is available, otherwise, the user is notified about the unavailability.
5. Once the user clicks on the view cart button, the user is asked to log in and then navigated to the view cart page and open the links and store the cart info in the database.
6. Then there is the end, which is displayed as a black circle with a red outer circle

References — https://www.visual-paradigm.com/guide/uml-unified-modeling-language/what-is-activity-diagram/