Most people have acquaintances and colleagues, but friendships are a little bit harder to define. How do you know someone is your friend? And if they are your friend, how deep is that friendship?

Here are signs to help you know if the person you like is a real friend.

1. They respond well to your presence

This is perhaps the most obvious and easiest sign of friendship. Smiles and gestures of respect are the first signs of friendship, but they are also a sign that the other person likes you for who you are.

2. They are willing to give you their time

Time is precious, and people who are prepared to either talk or simply hang out may be considered a friend. A friend, after all, is someone you enjoy spending time with.

3. They are willing to join you in your activities

This comes later in the relationship, but people who are willing to join you in your hobbies and activities may be considered friends. They may not even like your hobbies, but the fact that they are willing to join you is proof of their admiration for you.

4. They don't want to displease you

Although many people claim that they want their friends to be honest with them, we also appreciate friends who frame their criticisms in a nice way. Friends don't want to hurt your feelings, and that's a good thing.

5. They challenge you to improve yourself

Self-improvement is very important, and good friends can help you achieve such goals. In fact, a good friend may even help you in whatever endeavor you're interested in, whether it's a new hobby or developing a new skill.

6. You can talk to them for a long time

Friends like to talk, and good friends can talk for hours at a time. When two people like to talk to each other about just about everything, then they are most likely good friends.

7. They are supportive of your ideas

We all have ideas - some good, and some not so good. Friends will support your good ideas and offer constructive criticisms of the bad ones. So welcome them for what they are.

8. They like what you like

Real friends often like the same things, whether it's politics, pop-culture, or even food. Of course, not all friends share the same interests, but this is more often the case than not.

9. You are comfortable in their presence

Friends make you comfortable. More importantly, they can also make you feel at ease even when you are in a difficult situation or setting. They can also be a source of comfort during difficult times, even when they aren't doing anything.

10. They compliment you personally

Sometimes, a friend is a person who compliments your skills and personality. For example, they are personable where you are quiet. They can also be laid-back where you are driven. What makes these types of friendships so great is that they prove the adage: Opposites attract. If you can be friends with someone who is the opposite of your personality, then they can make your life a little more interesting.

11. You just click

Finally, there are friendships where both people just "click." This connection can be due to any number of causes, but what's important is that the spark is there and from that spark, friendship grows. If you "click" with a person, that may be the start of a beautiful friendship.