> **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
The type `T.untyped` represents a type that Sorbet has no specific knowledge| sorbet.org
Sorbet supports abstract classes, abstract methods, and interfaces. Abstract| sorbet.org
Sorbet has syntax for creating generic methods, classes, and interfaces.| sorbet.org
As we've mentioned before, Sorbet is a [gradual](/docs/gradual) system: it can be| sorbet.org
RBI files are "Ruby Interface" files. Sorbet uses RBI files to learn about| sorbet.org