# Welcome to Gel

Gel is a next-generation [graph-relational database](https://www.geldata.com/blog/the-graph-relational-database-defined) designed as a spiritual successor to the relational database.

It inherits the strengths of SQL databases: type safety, performance, reliability, and transactionality. But instead of modeling data in a relational (tabular) way, Gel represents data with *object types* containing *properties* and *links* to other objects. It leverages this object-oriented model to provide a superpowered query language that solves some of SQL's biggest usability problems.

## How to read the docs

Gel is a complex system, but we've structured the documentation so you can learn it in "phases". You only need to learn as much as you need to start building your application.

- **Get Started** — Start with the [quickstart](https://docs.geldata.com/learn/quickstart/overview/nextjs.md#ref-quickstart). It walks through Gel's core workflows: how to install Gel, create an instance, write a simple schema, execute a migration, write some simple queries, and use the client libraries. The rest of the section goes deeper on each of these subjects.

- **Schema** — A set of pages that break down the concepts of syntax of Gel's schema definition language (SDL). This starts with a rundown of Gel's primitive type system ([Primitives](https://docs.geldata.com/reference/datamodel/primitives.md#ref-datamodel-primitives)), followed by a description of ([Object Types](https://docs.geldata.com/reference/datamodel/objects.md#ref-datamodel-object-types)) and the things they can contain: links, properties, indexes, access policies, and more.

- **EdgeQL** — A set of pages that break down Gel's query language, EdgeQL. It starts with a rundown of how to declare [literal values](https://docs.geldata.com/reference/edgeql/literals.md#ref-eql-literals), then introduces some key EdgeQL concepts like sets, paths, and type casts. With the basics established, it proceeds to break down all of EdgeQL's top-level statements: `select`, `insert`, and so on.

- **Guides** — Contains collections of guides on topics that are peripheral to Gel itself: how to deploy to various cloud providers, how to integrate with various frameworks, and how to introspect the schema to build code-generation tools on top of Gel.

- **Standard Library** — This section contains an encyclopedic breakdown of Gel's built-in types and the functions/operators that can be used with them. We didn't want to clutter the **EdgeQL** section with all the nitty-gritty on each of these. If you're looking for a particular function (say, a `replace`), go to the Standard Library page for the relevant type (in this case, [String](https://docs.geldata.com/reference/stdlib/string.md#ref-std-string)), and peruse the table for what you're looking for ([`str_replace()`](https://docs.geldata.com/reference/stdlib/string.md#function::std::str_replace)).

- **Client Libraries** The documentation for Gel's set of official client libraries for JavaScript/TypeScript, Python, Go, and Rust. All client libraries implement Gel's binary protocol and provide a standard interface for executing queries. If you're using another language, you can execute queries [over HTTP](https://docs.geldata.com/reference/using/http.md#ref-edgeql-http). This section also includes documentation for Gel's [GraphQL](https://docs.geldata.com/reference/using/graphql/graphql.md#ref-graphql-overview) endpoint.

- **CLI** Complete reference for the `gel` command-line tool. The CLI is self-documenting—add the `--help` flag after any command to print the relevant documentation—so you shouldn't need to reference this section often.

- **Reference** The *Reference* section contains a complete breakdown of Gel's *syntax* (for both EdgeQL and SDL), *internals* (like the binary protocol and dump file format), and *configuration settings*. Usually you'll only need to reference these once you're an advanced user.

- **Changelog** Detailed changelogs for each successive version of Gel, including any breaking changes, new features, bigfixes, and links to

## Tooling

To actually build apps with Gel, you'll need to know more than SDL and EdgeQL.

- **CLI** — The most commonly used CLI functionality is covered in the [Quickstart](https://docs.geldata.com/learn/quickstart/overview/nextjs.md#ref-quickstart). For additional details, we have dedicated guides for [Migrations](https://docs.geldata.com/learn/migrations.md#ref-intro-migrations) and [Projects](https://docs.geldata.com/reference/using/projects.md#ref-guide-using-projects). A full CLI reference is available under [CLI](https://docs.geldata.com/reference/using/cli.md#ref-cli-overview).

- **Client Libraries** — To actually execute queries, you'll use one of our client libraries for JavaScript, Go, or Python; find your preferred library under [Client Libraries](https://docs.geldata.com/reference/using/clients.md#ref-clients-index). If you're using another language, you can still use Gel! You can execute [queries via HTTP](https://docs.geldata.com/reference/using/http.md#ref-edgeql-http).

- **Deployment** — To publish a Gel-backed application, you'll need to deploy Gel. Refer to [Guides > Deployment](https://docs.geldata.com/reference/running/deployment.md#ref-guide-deployment) for step-by-step deployment guides for all major cloud hosting platforms, as well as instructions for self-hosting with Docker.


Gel features:

- strict, strongly typed schema;
- powerful and clean query language;
- ability to easily work with complex hierarchical data;
- built-in support for schema migrations.

Gel is not a graph database: the data is stored and queried using relational database techniques. Unlike most graph databases, Gel maintains a strict schema.

Gel is not a document database, but inserting and querying hierarchical document-like data is trivial.

Gel is not a traditional object database, despite the classification, it is not an implementation of OOP persistence.