An achievement is a goal for a member. You will choose between range and score types which will be explained below. When a user earns an achievement, it will be displayed on their activity screen and you will get a notification that they have achieved it.
You can handle marking these achievements as seen in the club management section of this web app.
A range-type achievement has a start date, an end date, and a number of times that the member must check-in to earn the achievement.
An example would be if you wanted your members to check-in once a week for each week between January and the end of March. You would count the number of weeks between January 1st and March 31st and use that as the score required.
Another use for this is rewarding your members for their first check-in. If you specify the start date as way in the past (ex Jan 28th 1985) and the end date way in the future (ex Jan 28th 2121) and the score to be 1, they will earn the achievement on their first check-in.
A score-type achievement is just like it sounds. You specify a score that your member must achieve and when they get that score, they get that achievement.