There are four ways in, and they all end in the same list.
Add one. A name plus a mobile number or an email address. One of the two is enough — you do not need both.
Paste a list. Copy anything that has names and numbers in it — a group text, a note on your phone, a column out of a spreadsheet — and paste it in. We show you what we read out of it before anything is added, and we flag anyone who is already on the event so you don't invite them twice.
From contacts. On browsers that allow it, mostly Chrome on Android, you can pick people straight out of your phone's contacts. On an iPhone the browser does not offer this, so the row says so and points you at paste instead. We would rather tell you than show a button that does nothing.
Upload a CSV. For hosts arriving from Evite or Paperless Post with a list already exported. A column of names and a column of numbers or addresses is all it needs.
After you send, we offer to save that set of people as a group. Next time they are one tap.