Friends are one of the most valuable things you can have in life!
Friends are always there for you when things in life get tough! They are also there with you to share in the joys of your life. Friends do many things for you, some noticed and some unnoticed. Always be grateful to have good friends!
Never replace your friends with significant others. They were there first and will most likely be there after. If that's not the case, it is because your significant other was the one, which in that case I hope they also became a friend.
If you're very lucky your family will also turn into your friends at some point. Then everyone close to you in life will be your friend. Trust me it's better to be rich in friends than money. (I mean it's great if you can have both, though!)
Never take your friends for granted no matter how much you fight or how much time passes between the times you see them. You can never replace a good group of friends or the memories and experiences you have gained from having them in your life!
Go tell your friends how much you appreciate them!