Generally, the sales life cycle starts with Lead generation. A lead is your potential customer. When an individual or a company shows any interest in your product/service and provides some details for further communication, then it is considered a lead:

The salesperson either manually enters the details of the lead into the CRM or captures the details through mails, websites, phone calls, campaigns, and so on. It requires a lead name (first name and last name) and a topic that describes the lead.

After lead creation, the salesperson does multiple activities to convert it to a customer. This can be done in form of appointments, phone calls, and emails to gather more information about the customer. If the customer gives a positive response, then Lead is qualified to an Opportunity. A contact and an account record is created after lead qualification. If the lead is disqualified, the sales process ends.

Once the lead is qualified, the salesperson gives quotes to the customer. Quotes can be revised multiple times until the customer agrees. Once the customer agrees with the quote, the opportunity is won; otherwise, the opportunity is lost and the sales process ends.

After winning an opportunity, an order is placed and an invoice is created after the order is delivered to the customer.