Do I need to tell people that I'm depressed?

You don't need to tell anyone about being depressed, but if it's lasting a long time or interfering with your social or professional life, then chances are you may want to talk to someone about it, even though it may be very difficult because of fear of some negative outcome. Being depressed is bad enough. Feeling alone when depressed is far worse. Sometimes it's not so much about someone being able to give advice, but rather that someone bears witness to what you are feeling. That in and of itself can relieve some of that knotted up feeling inside, even if for a little while. You aren't alone in being depressed. Many people hide it for any number of reasons. If you are questioning if you should tell someone, it's likely that you should.

You don't need to tell the world but communication can be really helpful in a safe, judgement free zone

Depends on yourself. There is no shame in accepting that you can't handle everything on your own. Humans aren't meant to stand alone and just remember that there is always options and venues for support. It may be uncomfortable talking about your feelings but that is normal. Just make sure you tell people you trust and do it in a safe environment.

I'm definitely not obligated to tell anyone that I'm depressed. I do not hide it though, because I want to make sure that the friends I make are mature enough to accept me with my depression.

Yes, seek professional help, as they are best suited to these situations and how to handle them! It'll help you understand your position and what to do about it :)

You don't need to exactly shout it out to everyone but you should confide in persons of trust. It is impratant not to keep it down low.

It would probably help you, it's likely that they don't know what's going on and they might get the wrong idea. But telling them just isn't enough, you have to make sure they understand depression otherwise they might not help you in the best way.

Yes, it is very helpful to open up to others and let them know your state of depression. It's not a mood you get over with by smiling, it's a mental condition that requires just as much attentions as any physical illness and by letting others know you're helping yourself.

You don't "need" to, but it can be helpful because it can explain your behavior. Sometimes people mistake symptoms of depression for laziness or dislike of them personally. Some people (like potential employers) may be prejudiced against you if you disclose depression, though, so you just need to make a decision each time based on the circumstances.

Sometimes when you depressed, you don't have to tell anyone it will be all over your face and your posture.