Entities

We use plural nouns when we're dealing with a collection and singular nouns when dealing with individual items. That's obvious, but it may not be so obvious in practice.

Singular

Class names should be singular as they are used to create a single object instance.

public class User { ... }

Plural

users.query(...);

When routing in a directory to find a specific resource, the higher level should be treated as a collection of such resource. In RESTful APIs, for example, the url to get a single resource should pass through a collection.

# Do
GET /users/1
GET /users

There was a project where I insisted using singular nouns for the high level resource and routes to a list if needed. Not only was that unintuitive, it also became messy as the collections grew.

# Don't
GET /user/1
GET /user/list

TIP

A more specific resource should have a longer address