It can be embarrassing to forget someone in a big group email — when you remember, do you forward the whole string, or resend it to everyone? To avoid alienating anyone, Gmail can help.
From home, open up Contacts. Start checking off people you'd like to add to a group (which you can edit to add more or delete later), and then click on the Groups drop-down to the right. Click Add to New Group, and a field will open asking what you'd like to name the group. Maybe you'd like a group for your book club, or everyone you usually invite to events. After entering the name, you've just created a Gmail group.
When you go to compose your next invite, just start typing the name of the group, and everyone in the group will get your email.