The who, what, when, where, and why of the party/event/gathering. That should do it good luck and have a great time at your party :)
It is a party that you need to receive an invitation to get in.
Write what the invitation is about. Write what you need to bring, who's it for, where, what time, if you need to RSVP, and what date, if there is a theme and other informative information.
If you received an invitation to the wedding then you do not need to bring the invitation to prove you were invited. If you never received an invitation to the wedding then it is not etiquette to attend the wedding and you would be considered crashing the wedding.
Assuming you mean the invitation to Ann's birthday party, if you get her past the black heart you should receive an invitation in your mailbox sometime in Fall. Then show up at the Inn at the time marked on the invitation and be sure to bring your invitation(you might not need this but it's better to be safe then sorry) and a wrapped gift(this you will need if you want to get anywhere with Ann).
An invitation
YES
Same as you would write a formal invitation (except for the letter head and its formality) but you need to assure him/her that the said invitation will be sent via courier and attach the formal invitation in the email as an advance copy (you are still bound to mail it).
They are dicks.
From their website:"Spotify free is currently in an invitation-only beta, which means you need to have received an invitation token to access the service."
To accept an invitation, on the email you have been sent there should be a link that says click on in. If you need an invitation send me an email at pitbull567@aol.com
Anyways, there isn't a need to have an invitation code already. You can just sign up for it without having already. I don't know if they'll change it back to where you need the invitation code in order to sign up, so better hurry before they change.
Yes, you may need an invitation letter to visit the USA, depending on your country of origin and the purpose of your visit. It is recommended to check with the U.S. embassy or consulate in your country for specific requirements.