Waivers put temporary freezes on unclaimed players, giving everyone a chance to make a claim on them. When this time period ends, all waiver claims are processed and the manager with the highest waiver priority gets the player. The league's commissioner can pick which waiver rule and waiver claim priority is used from the league settings.
You can choose from the following waiver types:
This is the default setting. Rolling waivers are continuous and the last person to waiver a player is placed last into the waiver priority. For every successful waiver claim, that team owner drops to the bottom of the order, while everyone else moves up one.
The waiver priority is reset every week based on the standings. Lower placed teams in the current standings will get highest waiver priority at the beginning of each NFL week.
Each manager is given a budget to bid on unclaimed players that are on waivers. The default budget is $100, but the commish of a Private League can adjust the budget as they see fit.
Commissioners also have the ability to edit FAAB budgets at any time via the mobile app by going into a team roster and tapping Edit FAAB budget.
You can learn more about FAAB bidding here: How does FAAB bidding work?