It is the percentage of customers (or users) that a company or app retains over a period of time. With an efficient retention rate calculation, marketers and developers can understand how their product is performing over time. 

Like many other critical KPIs, this rate is considered to be one of the most important metrics. It determines the success of a product. Models that enable decision-makers to fully understand customer parameters such as satisfaction, intent, loyalty, interest, and more.

The retention rate counter is the churn rate, which shows the percentage of users who stopped using your product in a given period of time. 

Retention rate is a measure of the percentage of customers who continue to do business with a company with company for a certain period of time.

If a company had 100 customers at the beginning of the year and 80 of those customers continued to do business with the company at the end of the year, the retention rate would be 80%.

Retention is an important metric for businesses because it is cheaper to retain existing customers or employees. Additionally, a high rate may indicate customer or employee satisfaction, which can lead to increased loyalty and company favors.