Concept states

Fields are attached to states (such as New, Assigned, or Closed). A state is a specific stage in the lifecycle of a lead record. A lead begins its life by being in a New state and ends with either a Won or a Lost state. In this process, the lead can pass through several other states also. For example, when a new lead is assigned to someone, it can move to an Assigned state, or when someone on your team fixes an appointment with a lead, the record might move to a Meeting scheduled state.

The following image shows state fields for a leads record.