A birthday party invitation is a written request sent to friends and family to attend a celebration of someone's birthday. It typically includes essential details such as the date, time, location, and theme of the party. Invitations can be sent in various formats, including physical cards, digital messages, or social media posts. The design of a birthday party invitation often reflects the interests of the birthday person, such as their favorite colors, characters, or hobbies. Some invitations may also include RSVP instructions, allowing the host to know how many guests will attend. This helps in planning food, activities, and decorations for the event.