Are you a heterosexual woman confused by your relationships with other females? Are you a guy, trying to understand why your girlfriend is inviting her sworn enemy to a dinner party? Interactions between women are complicated and nuanced. To mitigate the confusion, I offer you a typology of female relationships.

Forgettable Sue: You’ve been friends with this girl since college because she was on your freshman floor and happens to live in your neighborhood now, in real life. She’s as innocuous as she is forgettable, and usually named something like Sarah or Emily. You absentmindedly omit her from party invites and then have to send her a personal BCC-ed email so that she doesn’t realize she’s the only person on the list. You swear to god she has three birthdays a year, always on Tuesdays, on the far side of town at a pseudo-trendy, overpriced, annoying bar. You have to take two trains to get there and a taxi home. But you have to go, because you are friends.

And just to warn you — she’ll definitely get married before you. It will be at her family cabin in Michigan that is 2000 miles from the nearest airport that costs $800 to fly into. But you have to go, because you are friends.

Temp: You’re friends out of circumstantial convenience and loneliness. Your cubicles are adjacent, or she’s the only one with the same lunch shift. You get along fine, but as soon as you move or get a new job, you’re done. I recommend you discuss restaurants, her boyfriend (or lack thereof), and cute Internet memes. These girls are commonly named Jillian or “Jules.”

Insta-friend: You only interact for a brief period, but you’re totally kindred. This relationship occurs when you make a new friend on vacation or at a cousin’s wedding. You instantly bond as companions and confidents, and then part ways. I would take a bullet for these girls — not a fatal or particularly painful one, but one for sake of hyperbole. You keep these friends dear in your heart and like a lot of things they say on Facebook. Of course you do! You’re kindred!

Bridesmaids: These are your best friends. They would all be your bridesmaids if it were permitted or practical to have unlimited bridesmaids. You feel so cool when you’re going out together and so comfortable when you’re staying in together. You really want to get them meaningful birthday gifts and make them sentimental cards. And when you do neither because you have a life, they understand. They couldn’t care less because your friendship is the greatest gift! Plus, they know you’ll make it up to them later that night by being a great wing-woman and buying them unending, obnoxiously pink birthday drinks.

You can’t wait to be settled with respective husbands and meet up over brunch to nostalgically discuss your crazy 20s. In the mean time, you have a lot of brunches amidst your crazy 20s to prospect on being settled with your respective husbands.

Gay friends and Southern European men can also be Bridesmaids.

Frenemy: This is term has become cliché, but it is a very common and toxic relationship. You begin as friends, casual enough, and then somehow the friendship evolves into fierce, but unspoken antagonism. Well, unspoken to her face. Quite outspoken behind her back. You continue to socialize because 1) the social script for breaking up with a friend is unwritten, 2) you’re afraid that she’ll usurp your social identity if unsupervised, and/or 3) you need to collect more evidence to support that she is abominable, for when you talk behind her back.

You just want everyone to know that she is the worst! The stronger you feel this way, the more time you spend with her, and the more time you spend with her, the stronger you feel this way. The only way to eradicate an established Frenemy is for one of you to move out of social radius.

Nemeses: Counter-intuitively and unlike frenemies, nemeses are healthy, symbiotic relationships. They challenge and motivate you to excel — or, at least, to excel more than them. I could never advise on how to get a boyfriend, but I can tell you how to find a perfect nemesis.

She must share your aspirations in multiple realms such as social status, athletics, academics, student council president, hottest girl who works at Kinkos, etc. She doesn’t have to actively or consciously pursue these aspirations, but you know that deep inside, she covets all that ought to be yours.

1. She must rival you. Don’t pick someone easy to outdo. She must challenge you, which also means…
2. …She must be pretty. I’m sorry, but she must be pretty.
3. You are the same “type” as her (in the eyes of men) and you have the same “type” as her (with regard to men).
4. She is self-promoting and full of shit. You are genuine.
5. She makes desperate ploys for attention that are so deviously subtle that if you point them out, you sound like a crazy person!
6. For instance, she will make up a food allergy.
7. She likes to mention how she grew up on a farm and went to a public school. You know it was a historic apple orchard and a charter school in suburban Philadelphia where Asian children of doctors were considered “the diversity.” But you can’t point that out because why would you point that out? Pointing that out would mean admitting your malice.
8. She will feign ignorance about something just to make her background seem more Bohemian or hard-knock.
9. She might say, “Oh that’s steamed milk on those fancy coffee drinks? I always thought it was whipped cream.”
10. Or, “Who’s Topanga? I didn’t watch a lot of TV growing up.”
11. And you can’t accuse her of pretending to not know about Boy Meets World and lattes, because why would someone do that? You’ll look like the crazy person.
12. 7) Lastly, I recommend you go to the same gym at the same time as her. You’ll get such a better workout because you’ll have to go faster, stronger, longer, and with cuter outfits that you didn’t even try to put together than her.