Daily Active Users (DAU) is defined as the number of users who are active each day. The metric takes into account new users and existing users who have been active. A user is counted as active when he or she takes a certain action, this could be logging in or performing a transaction.
This metric can be calculated for every other time frame. Another common version is Monthly Active Users (MAU).
Note: Monthly average DAU is the average of Daily Active Users in a month.
Daily active users are calculated using the total number of unique users on a given day.
Total Daily Active Users = Number of unique users logged in on a given day
Σ unique active users
In January, 100 different people logged into the platform of a SaaS company and 50 returning users visited their existing account to do transactions
150 different people