You're in the receiving line, your groom at your elbow, and your great-aunt Mildred approaches to meet your one-and-only for the first time. This is the lady who taught you how to curtsey when you were four, eat an artichoke at 13, and distinguish a cabernet from a chardonnay on your 18th birthday. Now, on the very day you want to exude elegance, you hesitate. You know there's a way to show your respect to someone when making introductions, but it flies out of your head. What to do?
Remember this rule: when making introductions, you present the lesser "ranking" person to the senior person. Here's how to determine status:
An older person outranks a younger person.
Someone senior or more important at work outranks someone more junior or less important at work.
An out-of-town guest outranks a local guest of equal status.
A person serving a religious ministry outranks a lay person.
The way you present the person is simple: you say the name of the senior person first. Thus, in the case of your great-aunt Mildred, who outranks your groom by virture of the fifty-odd years she has on him, you say: "Auntie Mildred, may I present my husband, George Brown. George, this is my great aunt, Miss Mildred Fitzgerald." A more relaxed version of this would be: "Auntie Mildred, I'd like you to meet George Brown, my new husband," etc.
In the above introduction, you're assuming that George will be calling your aunt "Miss Fitzgerald" until she has given the go-ahead to call her anything more informal. It's a good rule of thumb to use the formal name of the senior person when making an introduction so that the junior person isn't placed in the awkward position of only knowing a senior person's very personal and intimate moniker. For instance, when introducing your boss to your teenage brother, you wouldn't say: "Bob, I'd like you to meet my brother, Billy. Billy, this is Bob, my boss." Instead, you'd say: "Billy, this is Mr. Greengate, my boss."
When you introduce someone to someone else of equal status, it doesn't matter who is presented to whom. However, it's thoughtful to make the introduction as informative as possible. Thus, if you're introducing your friend from the same department at work to your friend from the old neighborhood, try: "Jane, I'd like you to meet John Brown, my co-conspirator on our high-school yearbook. John, this is Jane Doe, who helps me keep my sanity at Acme Consolidated." Now they both have snippets of raw material to start a conversation.
Introducing your brand-new in-laws to guests at your wedding reception also requires a show of respect. Your in-laws will probably want you to address them in a more familiar manner as time goes on. However, etiquette dictates that you should continue to call them by the names you've been using (Mr. and Mrs. Brown, or Mr. and Mrs. B., for instance) since you met them. Tying the knot does not give you the right to start calling them Mom and Dad. Only they can give you permission to use a more intimate name and they will let you know what those names will be.
Many weddings these days will include a few extended family members. A wedding is a celebration of two families joining together, so introductions should include a brief explanation of how a family member, current or otherwise, relates to you. For instance: "Mr. Jones, I'd like you to meet my stepfather, Mr. Brown," or, "Mrs. Jones, I'd like you to meet Jane. Jane was married to my brother, Bob, and is now married to David Smith." Avoid going into an elaborate family history - or worse, revealing sordid details - when introducing an ex-family member to another guest. When introducing a couple who live together, whether they are straight or gay, it isn't necessary to delve into an explanation of their relationship. Simply say "Mr. Jones, I'd like you to meet Chris Smith and Tom Brown. Chris and Tom, this is Mr. Jones." The couple then have the choice of defining their relationship to their new acquaintance during the course of the ensuing conversation.
A final note: the bride and groom should be very clear on what the bride's last name is going to be before the wedding, so that when introductions are made there are no shocks or hurt feelings. If, for whatever reason, the bridal couple feel that the bride's choice of last name may be a sensitive issue with some members of the immediate family, they should ensure the family is aware of their decision well in advance of the wedding.