Birthday invitations are cards or digital messages sent to invite guests to a birthday celebration. They typically include important details such as the date, time, location, and theme of the party. Invitations can be designed in various styles, from simple and elegant to colorful and fun, depending on the birthday person's preferences. These invitations can be delivered in person, mailed, or sent electronically through email or social media. Many people also choose to include RSVP instructions, allowing them to know how many guests will attend. Overall, birthday invitations set the tone for the celebration and help ensure a successful gathering.