The Sales module in Dynamics CRM takes care of the entire sales process and the activities involved in sales. The Sales module has entities such as Contacts, Accounts, Leads, and Opportunity. These entities are used to store the information required in the sales process:

• Account: Account stores the information related to your customers, which can be a company or an organization. It can also contain records of stakeholders, vendors, business partners, or other organizations you interact with.
• Contact: This stores the information related to the people or individuals that are generally your customers or contacts of customers. Contacts are mostly related to a customer. Sometimes, a contact is not linked to any customer. In such cases, they are not related to any account.
• Lead: Leads are the potential customers generated from multiple sources, such as entering them manually, from company website, mails, or from other social media. If the lead is qualified, then they are converted to an opportunity.
• Opportunity: When your customer responds or shows some interest, then your Lead is converted to an Opportunity. An Opportunity can be won or lost.