Growing up, my mom always said to me and my sister, "No matter what, your sister will always be there for you." When you're in early elementary school, you're not listening to this "nonsense" because you're too focused on how your sister stole your favorite stuffed animal.

Back then, I shrugged off the phrase because I thought it was just a tactic to get my sister and me to stop bickering, but now, I have never heard truer words.

Not to be corny or anything, but my sister is my absolute best friend.

1. Secret keeper

Got an itch to tell a secret? Tell your sister. It's a judgment-free zone, but if she does judge you, she will be 100 percent and completely open about it. She will give her honest opinion on how she feels about your secrets.

2. 24/7 advice

Got a crisis at an ungodly hour? Most likely, she'll be awake. If not, wake her up by calling her 1,000 times!

3. Your wardrobe is 2x the size!

This could be a gift and a curse because 90 percent of the time, it's my sister stealing my clothes from my closet, but it does come in handy when I am frantically searching for something cute to wear.

4. She went through it all first

First day of high school, applying for college, moving into college, she was the first to do it all, so I wasn't in for any surprises.

5. Fights last two seconds

Whenever my sister and I argue, one of us will leave the room, and by the time we're in the same room again, it's as if the fight never happened. It's nice because looking back at some of our fights, they are so silly and easy to laugh at once it is over.

6. She's got your back

Hell hath no fury like a protective older sister. She will defend you until the end of time because that's what older sisters do.

7. #1 Best Friend

No matter what, my sister is always there for me. Through thick and thin, she's always there.

When we're young, we often take siblings for granted, but as we get older, they become your partner in crime.