Invitation; inviting someone or a group to an event, and also refers to invitations such as invitations letters/cards.
友人を誕生日パーティーに招待した。
I invited friends to my birthday party.
招待状には会場と開始時間が書いてある。
The invitation card states the venue and start time.
彼は講演のために海外から招待された。
He was invited from abroad to give a lecture.