The Sorbet syntax for type annotations representing arrays, hash maps, and other containers defined in the Ruby standard library looks different from other [class types](/docs/class-types) despite the fact that Ruby uses classes to represent these values, too. Here's the syntax Sorbet uses:| sorbet.org
> **Note**: Class types are used to describe values that are instances of a class---these are the most commonly used types. To instead learn about types for class objects themselves, see [T.class_of](/docs/class-of).| sorbet.org
> TODO: This page is still a fragment. Contributions welcome!| sorbet.org
Classes are also values in Ruby. Sorbet has two ways to describe the type of these class objects: `T.class_of(...)` and `T::Class[...]`.| sorbet.org
There are five ways to assert the types of expressions in Sorbet:| sorbet.org
This is one of three docs aimed at helping answer common questions about Sorbet:| sorbet.org
Sorbet implements a **control flow-sensitive** type system. It models control| sorbet.org
This doc will cover how to enable and disable the **static checks** that Sorbet| sorbet.org
> This page describes the syntax of method signatures, or `sig`s. For a complete| sorbet.org
A static type checker for Ruby| sorbet.org
The type `T.untyped` represents a type that Sorbet has no specific knowledge| sorbet.org
```ruby| sorbet.org
Sorbet provides the most value when it has a wealth of programmer-supplied| sorbet.org
Sorbet supports abstract classes, abstract methods, and interfaces. Abstract| sorbet.org
Sorbet can track when a value is allowed to be `nil`, or when a value of a| sorbet.org
Sorbet supports method override checking. These checks are implemented as `sig`| sorbet.org
RBI files are "Ruby Interface" files. Sorbet uses RBI files to learn about| sorbet.org