What is  a flow in salesforce ? what is the use of it ?

Flow is an application inside the Salesforce that automates a business process by collecting data and performing operations in your org or an external system. Flow can fetch, delete, update and create records on multiple objects. Flows in Salesforce can be implemented in two ways

Screen Flows
Auto-launched Flow

Screen Flows
In this type of flow, there will be a series of screen elements to gather information from the user and perform some operation. Screen flows can be accessed from custom buttons, custom links, Visualforce Pages etc. This type of flow is implemented if a user interaction is needed in the process.

Auto-launched Flow
Auto-screenshot runs in the background without any user interaction. Auto-launched flows can be accessed from custom buttons, custom links, Visualforce Pages, process builder and Apex etc.

Consider a business scenario, an organizationwith name ABC PVT LTD has Accounts Object. The requirement is that Opportunity for an Account should be created automatically when a button is clicked on Account object. This can be achieved by creating a flow and accessing the flow using a custom button. Now I’ll be showing you how to create a salesforce flow to meet the above requirement.