Class Methods Are Singleton MethodsSince in Ruby classes are objects as well, class methods are merely methods defined on a specific instance of Class.

An admonition is a parenthetical

Hypernymy, or the IS-A relation, is one of the most important lexical relations.

Taxonomies are often represented as is-a hierarchies where each level is more specific (in mathematical language "a subset of") the level above it. For example, a basic biology taxonomy would have concepts such as mammal, which is a subset of animal, and dogs and cats, which are subsets of mammal. This kind of taxonomy is called an is-a model because the specific objects are considered as instances of a concept. For example, Fido is-an instance of the concept dog and Fluffy is-a cat.

The is-a relationship may also be contrasted with the instance-of relationship between objects (instances) and types (classes): see Type–token distinction.

Turbolinks is a Single-Page Application Turbolinks doesn't just give you some of the benefits of a single-page app. Turbolinks is a single page app. Think about it: When someone visits your site, you serve them some HTML and Javascript. The JavaScript takes over and manages all subsequent changes to the DOM. If that's not a single-page app, I don't know what is.

Every URL is a URI; Every URN is a URI; URI and URL are NOT interchangeable – a URL is a URI, but a URI is not always a URL; URLs always contain an access mechanism.

Escaping is a subset of encoding, where not all characters need to be encoded. Only some characters are encoded (by using an escape character).

Encoding is transforming data from one format into another format.