What is Lightning Data Service in Lightning Component in Salesforce ?

Lightning Data Service is a centralized data caching framework which is used to load, save, create and delete a record without server-side apex code. It supports the sharing rules and field-level security as well. Lightning Data Service improves performance by eliminating the multiple SOQL query call for a single record from the multiple instances. Instead, components share a single copy of the record data by saving the record with its update state in the cache and eliminate refreshing the component when a record is updated.  If a user gets disconnected from the network, it allows him to work in offline with data. Data status gets updated once the network connection gets restored.