Communication is important in all kinds of relationships, whether it's a relationship between friends, lovers, colleagues, or family members. Sometimes, people fall into the trap of assuming that communications means being brutally honest and blunt with the person you're trying to communicate with. While this sometimes may be the case, it is not always so. It is important to know how to communicate depending on the type of situation you're in.
When I was in middle school, a teacher of mine gave me some very important advice that I still follow to this day. She told me that if you're ever trying to explain to someone why something they've done has upset you, then you should always use "I" statements. For instance, saying "I feel hurt by what you did" instead of saying "you always do stuff like this."
People have a natural tendency to become defensive if they feel like they're being attacked, which is why "I" statements are typically more effective in making them see your point of view. Another strategy which allows people to empathize with you is to put that person in your shoes. For instance, asking "how would you feel if I did this?".
In the age of technology, communication can ironically be harder than ever. A lot of people text differently than they would in real life, and sometimes words on a screen can carry a different meaning than words spoken in real life. Things like tone and emotion, which are often keystones in communication, cannot be conveyed through a text message. That's a big reason why I've always felt that, unless it's not possible, important conversations should ideally be held either over the phone or in real life.
As someone who is quiet and can be shy at times, I do understand the temptation to lean on text communication, as a large amount of people would rather avoid real-life conflict. But as hard as it can be, it's crucial to be able to talk to someone about problems in a relationship face to face.
One last thing which is important in communication is know not only what to communicate, but when to communicate. For instance, if you are in an argument with someone and find that it's become heated, you should know when to exit the conversation and take a break for a while, especially if you're at the point where the conversation is no longer constructive.
In the end, communication is how humans learn to cooperate and get along. It is the cornerstone of every relationship.