Dynamics CRM is comprised of a few standard elements working together to achieve the system's functionality. These include, but are not limited to, modules and entities.
Modules are a group of functionalities that serve a specific business scope. The standard modules provided by Microsoft include sales, service, and marketing.
The sales module deals with all the functionalities needed to progress a lead to fruition.
The service module focuses on tracking activities related to interactions with existing customers. This module focuses on caring for customers and helps the representatives build a better relationship with existing customers.
The marketing module deals with engaging existing and potential customers by facilitating marketers to plan, execute, and gauge the success of campaigns that engage customers across multiple channels. This module also helps marketers quantify the success of each campaign and the impact of your marketing efforts.