Traditional writing has many rules. Write vertically. Invite the other party in the name of the highest and most respected person in the family (generally male elders, if only the mother has the highest seniority, add the word "Daici" after signing). The red paper used for the invitation is divided into four editions, the big one is divided into eight editions, and the bigger one is 12 edition. The cover says "Invitation". Please look up and write down the address of the invited person with the old honorific name (Oh, where did people who grew up in New China learn this). Then get down to business and state the time and place of eating (going to eat), the invitation items, and the party (of course, it is usually the younger generation). You can't write "marriage" when you get married, you should write "flowers and candles are beaming" and "housewarming is beaming" when you move to a new home. So most of them were written by someone.
The new writing is much simpler, and the format inside can refer to writing letters. The cover is also an invitation. Generally, you can invite each other in your own name and address them as "comrades" and "gentlemen". State the time, place and thing, and finally sign it.
Few people write invitations in person now. Generally, the printed "invitation" is bought back (mainly regardless of the "format"), and the name, address, invitation items, dinner time and place of the other party are filled in, and the signature of the inviter is signed. Simple and convenient.