Text them randomly.

Sending someone a random text and just saying, "Hey, how are you?" can really be a reminder that you're there for them. This is a simple, small act that will take just a few seconds of your time.

Write them a letter.

There is truly nothing quite like snail mail. Again, sending someone a small card will remind them that, hey, you want to talk to them. You think about them. You care about them.

There's something inexplicably special about receiving something in the mail from a friend who lives far away, knowing that they sat down and wrote their letter to you and that you're now holding that same letter in your hand.

This is the same idea as sending a text, but so much more thoughtful.

Get them a gift.

This doesn't have to be anything crazy. It can be a candy bar or a bag of chips.

Giving someone a gift is just a way to show people that you pay attention to what they like and that you think about them when you're not with them.

Hug them.

Most people aren't going to be mad if you show them some friendly affection with a hug. Sometimes we all just need a hug. So hug your friends. It's pretty simple.

Spend time with them.

Grab a drink. Watch a movie. Go out to eat. Do homework together. Even simply sitting next to them in class or in the break room at work will let them know you like them.

Choosing to spend time with someone is a good way to let them know that you enjoy spending time with them. Which would also imply you care about them.

Ask how they're doing.

Let them know you're really making sure they're OK. Ask if they've eaten today, if they have taken a shower, if they need to talk about something.

Compliment them.

Be genuine, but compliment the people you care about frequently. It let's them know you pay attention to the little things about them. It shows your appreciation for the things they do or the ways they are. Getting a good compliment can lift someone's mood on any day.

Do them a favor.

Offer to take out their trash or walk their dog. Do their dishes. How does this show them you care? I don't know, really, but I feel like doing something for someone else, for free, even without them asking, just means you want them to have one less thing to do at the end of the day.

Listen to them.

Pay attention. Take notes of what they like and don't like. Let them vent to you. Let them tell you all about their day in all the good and bad ways.

Tell them.

Sometimes, you have to be up front and just say you care about someone. There's nothing wrong with saying it, but I do think it's better to show you care... however, if all else fails, use the power of your words.