Front-End Development Libraries Certification

JSON is a text format for exchanging structured data: values are strings, numbers, booleans or null, arranged in ordered arrays and in objects of name and value pairs, and every mainstream language reads and writes it without a library of its own.

GraphQL is a query language for APIs and a server-side runtime for answering those queries: a client asks for precisely the fields it needs from a typed schema, in one request, instead of calling several fixed endpoints and discarding most of what comes back.

Microservices is an architectural style in which one application is built as a set of small services, each running in its own process, owning its own data and talking to the others over lightweight network calls, so that each can be built, deployed and scaled on its own.

Cloud hosting is the model in which servers, storage and databases are created on demand through an API from a provider's pooled hardware and billed for the time they exist, rather than rented as a fixed box by the month.

A web server is the program listening on a network port for HTTP requests and answering them, either by returning a file from disk or by handing the request to application code behind it.

Load balancing is the practice of putting one entry point in front of several interchangeable servers and distributing incoming requests among them by a chosen policy, so that no single machine carries the traffic and no single machine's failure takes the service down.