---
title: Ruby Documentation Index
description: Curated map of the Ruby language and standard library, maintained by RubyDoc.AI.
canonical: https://rubydoc.ai/docs.md
source: RubyDoc.AI
---

# Ruby Documentation Index

Curated map of the Ruby language and standard library, maintained by RubyDoc.AI. All links resolve to the official documentation at docs.ruby-lang.org and ruby-lang.org.

## Core · Basics

_Fundamental value types every Ruby program uses._

Canonical: https://rubydoc.ai/docs/core-basics.md

- [Object](https://docs.ruby-lang.org/en/master/Object.html) — Root of Ruby's object hierarchy.
- [String](https://docs.ruby-lang.org/en/master/String.html) — Mutable sequence of characters.
- [Symbol](https://docs.ruby-lang.org/en/master/Symbol.html) — Interned, immutable identifier.
- [Integer](https://docs.ruby-lang.org/en/master/Integer.html) — Whole numbers of arbitrary size.
- [Float](https://docs.ruby-lang.org/en/master/Float.html) — Double-precision floating-point numbers.
- [Numeric](https://docs.ruby-lang.org/en/master/Numeric.html) — Abstract base of all number types.
- [TrueClass / FalseClass / NilClass](https://docs.ruby-lang.org/en/master/NilClass.html) — Boolean & nil singletons.
- [Range](https://docs.ruby-lang.org/en/master/Range.html) — Interval of values, e.g. (1..10).
- [Regexp](https://docs.ruby-lang.org/en/master/Regexp.html) — Regular expression pattern.

## Core · Collections

_Data structures and iteration._

Canonical: https://rubydoc.ai/docs/core-collections.md

- [Array](https://docs.ruby-lang.org/en/master/Array.html) — Ordered, mutable list.
- [Hash](https://docs.ruby-lang.org/en/master/Hash.html) — Key/value dictionary preserving insertion order.
- [Set](https://docs.ruby-lang.org/en/master/Set.html) — Unordered collection of unique values.
- [Enumerable](https://docs.ruby-lang.org/en/master/Enumerable.html) — Mixin providing map, select, reduce & friends.
- [Enumerator](https://docs.ruby-lang.org/en/master/Enumerator.html) — Externalize iteration; build lazy pipelines.
- [Comparable](https://docs.ruby-lang.org/en/master/Comparable.html) — Mixin for ordering via <=>.

## Core · Classes & Modules

_The building blocks of Ruby's object model._

Canonical: https://rubydoc.ai/docs/core-classes.md

- [Class](https://docs.ruby-lang.org/en/master/Class.html) — Blueprint for objects.
- [Module](https://docs.ruby-lang.org/en/master/Module.html) — Namespace and mixin container.
- [Method / UnboundMethod](https://docs.ruby-lang.org/en/master/Method.html) — First-class method objects.
- [Proc / Lambda](https://docs.ruby-lang.org/en/master/Proc.html) — First-class blocks / closures.
- [Kernel](https://docs.ruby-lang.org/en/master/Kernel.html) — Methods available on every object (puts, require, ...).

## Core · IO & Files

_Reading, writing, streams and processes._

Canonical: https://rubydoc.ai/docs/core-io.md

- [IO](https://docs.ruby-lang.org/en/master/IO.html) — Base class for input/output streams.
- [File](https://docs.ruby-lang.org/en/master/File.html) — File I/O and path operations.
- [Dir](https://docs.ruby-lang.org/en/master/Dir.html) — Directory traversal and globbing.
- [Pathname](https://docs.ruby-lang.org/en/master/Pathname.html) — Object-oriented file paths (stdlib).
- [StringIO](https://docs.ruby-lang.org/en/master/StringIO.html) — IO-like interface over a String.

## Core · Errors & Control

_Exceptions, control flow, threading._

Canonical: https://rubydoc.ai/docs/core-errors.md

- [Exception](https://docs.ruby-lang.org/en/master/Exception.html) — Root of the exception hierarchy.
- [StandardError](https://docs.ruby-lang.org/en/master/StandardError.html) — Default rescue target.
- [Thread](https://docs.ruby-lang.org/en/master/Thread.html) — Native threads.
- [Fiber](https://docs.ruby-lang.org/en/master/Fiber.html) — Cooperative micro-threads.
- [Mutex / Queue](https://docs.ruby-lang.org/en/master/Mutex.html) — Synchronization primitives.

## Standard Library

_Batteries shipped with Ruby._

Canonical: https://rubydoc.ai/docs/stdlib.md

- [JSON](https://docs.ruby-lang.org/en/master/JSON.html) — Parse and generate JSON.
- [Net::HTTP](https://docs.ruby-lang.org/en/master/Net/HTTP.html) — HTTP client.
- [URI](https://docs.ruby-lang.org/en/master/URI.html) — Parse and build URIs.
- [OpenStruct](https://docs.ruby-lang.org/en/master/OpenStruct.html) — Objects with arbitrary attributes.
- [Struct](https://docs.ruby-lang.org/en/master/Struct.html) — Value objects generated at runtime.
- [Date / Time / DateTime](https://docs.ruby-lang.org/en/master/Time.html) — Dates, times, and arithmetic.
- [CSV](https://docs.ruby-lang.org/en/master/CSV.html) — Read/write CSV data.
- [YAML](https://docs.ruby-lang.org/en/master/Psych.html) — YAML via Psych.
- [Logger](https://docs.ruby-lang.org/en/master/Logger.html) — Structured logging.
- [OptionParser](https://docs.ruby-lang.org/en/master/OptionParser.html) — Build CLI flag parsers.
- [SecureRandom](https://docs.ruby-lang.org/en/master/SecureRandom.html) — Cryptographic-grade randomness.
- [Digest](https://docs.ruby-lang.org/en/master/Digest.html) — MD5/SHA hashing.

## Language & Guides

_Learning material from ruby-lang.org._

Canonical: https://rubydoc.ai/docs/guides.md

- [Getting Started](https://www.ruby-lang.org/en/documentation/quickstart/) — A tour of Ruby in ~20 minutes.
- [Ruby From Other Languages](https://www.ruby-lang.org/en/documentation/ruby-from-other-languages/) — Ruby for Python / JS / Java devs.
- [Ruby's Style Guide](https://www.ruby-lang.org/en/documentation/) — Idiomatic Ruby patterns.
- [Syntax Reference](https://docs.ruby-lang.org/en/master/syntax.html) — Full grammar & syntax pages.
- [Regexp syntax](https://docs.ruby-lang.org/en/master/Regexp.html) — Pattern language reference.
- [Pattern Matching](https://docs.ruby-lang.org/en/master/syntax/pattern_matching_rdoc.html) — case/in destructuring.
- [Refinements](https://docs.ruby-lang.org/en/master/syntax/refinements_rdoc.html) — Lexically-scoped monkey patches.
- [Ractor](https://docs.ruby-lang.org/en/master/Ractor.html) — Parallel actor model.