A popular project management method used in different industries. It allows close collaboration and addresses rapidly changing requirements in complex projects.
An agile project is broken down into sprints identified by start and end date. Each sprint contains any number of tasks, that need to be completed during that sprint. Regular (daily or weekly) meetings, either in person or online, help the team to stay in control and to early identify possible issues.
An agile project needs a budget, not an estimate. The budget dictates what and how features can be realized. The sprint meetings do help the team and the management to identify features that may exceed their budget and to take appropriate action early on.