We’ve all been there. Unfortunately, for whatever reason, a person whom you considered to be a very close friend went behind your back and revealed something you told them in confidence, or did something else to betray your trust. I don’t know about you, but my trust is extremely hard-won, and when someone betrays it, it’s pretty hard to get that faith back.

When I was describing such an incident to one of my friends last week, she listened along with sympathy and replied matter-of-factly: “Oh, she’s just a red-light friend then.” I stared back at her, confused. “Red-light” friend? Since when are we comparing friendships to traffic lights?

As she went on to further explain, I found the metaphor to hold a lot of merit, and to be a pretty good way of separating out different types of friendships. So, without further ado, here are the three types of friendships one might have: red light, green light, or yellow light.

Red light: Remember when I said a friend of mine betrayed my trust? That’s one of the best examples of a red-light type of friend. Sure, everyone messes up sometimes and reveals something that they shouldn’t have. However, when your friend seems to be doing this consistently and further upsets you by making rude or unnecessary comments, they’re going to be a red-light type of friend.

You don’t expect much from red-lights, because they don’t really do much to earn that kind of expectation. They make you stop and think before you confide in them or ask them for some kind of assistance because they are unreliable. You can make dinner plans with a red-light friend, but you’re not exactly surprised or upset when they cancel. You manage your expectations to what you know about this friend, based on your history with them. These types of friends are not particularly the kind you want to be your bridesmaids, but they’re good for a laugh every now and then.

Yellow light: This category is a little trickier. These friends are typically the ones you sit next to in class, or maybe they’re one of the girls in your sorority who you’ve only talked to a couple times. Whatever the case, you like them, but you don’t really know them all that well. Hence, you take a pause and slow down before you tell them anything personal, because, well, you’re not really sure what they’re going to do about it.

You definitely have every opportunity to become better friends with a yellow-light, and it depends on whether you’re willing to put the work in. The main distinction between a red and yellow light is that red-lights have shown you that they can’t be trusted. Yellow lights have the opportunity to show you that they can be trusted, and maybe eventually become closer with.

Green light: Finally, we have your green-light friends. These friends are the ones that you want to hold on to. You trust them with your secrets and thoughts, and go right ahead and confide in them without any worry about the possible repercussions.

They’ve shown you that they can be trusted, and support you and help you with any issues that you may encounter. You trust them whole-heartedly, and they, in turn, trust you. They’re your go-to’s, the ones you go to dinner with and rely upon for advice and support. These are the friends you want in your life for years to come. Green-lights friends are rare, and their presence in your life is invaluable.