A few years ago, a friend of mine told me something that really changed my way of thinking about friendship and what it means. I was feeling down one day, and in an effort to cheer me up and re-boost my confidence, she said, "Every rainbow needs purple in it" (referring to my recently-dyed-purple hair). It really touched me, not only because she succeeded in making me feel better, but also because it served as a reminder that this person appreciated my unique qualities. She felt that I added something to her life that she might not have otherwise.

Every color of the rainbow is different--in appearance, of course, and scientifically, but also in terms of the mood they create, and the ideas and feelings they symbolize. In the same way, every person is different. We have different personalities, different interests and different ways of expressing ourselves. But in a group of friends, every different person brings something that the group as a whole would be incomplete without.

1. The shoulder to cry on.

When life gets tough, when you start to feel like everything is falling apart, this friend is your pillar of strength. You can go to them with any problem, no matter how big, and you know they will give you their undivided attention, listen carefully and offer their support. Even if this friend doesn't completely understand exactly what you're going through, they will assure you that you're strong enough to survive it, and that they will be there every step of the way to help you through it.

2. The adventurer.

This is the friend who's up for anything at any moment. The one who makes certain that your life is never dull, a recurring character in your crazy stories. These friends are especially awesome to have around when you're feeling lazy and sluggish, because they'll find a way to bring out your adventurous spirit. The perfect partner in crime.

3. The jokester.

As we transition into adulthood, life can feel really serious and stressful all the time. That's why it's important to have friends who keep things light and eliminate the stress with their fantastic humor and silliness. Daily laughter is important for our mental health, so having a friend who makes you giggle non-stop is awesome.

4. The truth-teller.

Sometimes, in certain situations, we get caught up in our own thoughts, feelings and opinions and we just need someone to tell it like it is. These friends will never hold back about anything, which also makes them great people to go to for advice. Not as soft-hearted and sensitive as the shoulder-to-cry-on types, brutally honest friends sometimes may not even realize that the things they say have the potential to sting a little. But they always have your best interest at heart.

5. The quiet thinker.

Shy people often have it tough in friend groups because they have a hard time making their opinions heard. But it's so important to have friends who speak less and observe more, because you know everything they do say will be insightful and well worth listening to. Quiet thinkers take a more measured approach to life, and they can be excellent voices of reason (especially when those adventures start to get a little too adventurous).