The Use Case Model presents how different users interact with a system, describing the needs of a user and the interaction between the user/system. Use case modeling identifies and models business events, showing who initiates them and how the systems respond to it. The Use Case model at its basic level  contains at least 3 elements: An Actor, a Use case, and the Association. The Actor is a person, stakeholder, or entity involved in the system which is usually represented with a name and a brief description. The Use Case is a system function that happens within the system. And Association is the link between the actor and Use case that shows the participation within the use case model.

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In software development, developers will be given an assignment to complete a certain application or introduce improvements depending on the project. Use case models can help in this problem by defining the relationship between actors and the use case. Modeling the dependencies between actors can show the functions that currently take place in the model which can be helpful, the developers can then analyze different aspects of the model to make changes that will increase the efficiency of the system. 

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Take for example the use case model of a Bar. Where a customer will interact with the bar by ordering a drink. Another actor in the system, the vendor will then supply drinks to the bar to be sold. Two interactions that are shared will be that the customer and the vendor will be able to see the receipt and the transaction of funds inside the system. This use case model has shown the relationship that takes place inside the bar. This model can then be analyzed to see which aspect of the business can be modified. Use case models are a very useful tool to help analyze a system.