DEFINITION What is Invitation? Do you know the word "invite"? Yes, Invitation is the noun from "invite". And are you understanding "letter"? Yes, this thing usually exists in post office. Invitation is a written or spoken request to come to an event like party, celebration, a dinner, or meeting quoted in Collins Dictionary. Invitation Card A card or pamphlete that used to invite someone or people to attend the event. KINDS It divides to 2 forms of invitation letter/card such as: 1. Formal Invitation This type is constructed to inform person in institutes, company, or et cetera. 2. Informal Invitation It is usually made in casual situation like we want to invite friend, family, or it can be someone special to birthday party, wedding celebration, or another event. HOW TO SAY: a) When invite someone • You are invited to.. • Would you like to come on.. b) When respond to come or not • Yes, i'm glad to come. • Sorry, I have another plan. EXAMPLE: 1) Birthda...