GraphQL is a query language for API interfaces, implemented in 2012 by Facebook as a response to the need to increase the efficiency of newsfeed loading on mobile phones. It is a very flexible and rich query language, and its main functionality is mapping relations between objects in a database or any other data source and creating graphs on this basis. It allows you to define the structure of the required data, which has a very positive effect on unification and consistency.
Flexibility, the richness of the query language and the ability to combine multiple data sources into one consistent interface are irreplaceable in the era of serverless and microservices. It consists of a type system, query language and execution semantics, static validation, and type introspection.