A flow is an application that automates a business process by collecting data and performing operations in your org or an external system. Flows can also manipulate data in your org by creating, updating, deleting, or submitting records for approval. You can use flows to update fields on related records when a certain event occurs, such as closing a work order. In this case, a flow can be used to update the last maintenance date field on the Asset record when a maintenance work order gets closed.