Dependency

Something a class needs in order to do its job, like a database or an email sender.

What is Dependency?

A dependency is something a class needs in order to do its job, such as a database connection, an email sender or a clock.

public class OrderService
{
    private readonly IEmailSender email; // a dependency

    public OrderService(IEmailSender email) => this.email = email;
}

Level: Journeyman · More OOP terms at this level

Updated September 27, 2026