The Ant Migration Tool is a Java/Ant-based command-line utility for moving metadata between a local directory and a Salesforce organization. You can use the Ant Migration Tool to retrieve components, create scripted deployment, and repeat deployment patterns.
A free tool from Apache that can be used for scripting build operations and in the case of Salesforce, retrieve and deploy one Salesforce org’s metadata to any other org. ANT uses XML instructions to perform the appropriate operation like deploy, retrieve, list metadata and so on