The meaningful units of communication, the base of this world's society. Without them, people would not be able to connect with each other, to live with one another. Then, if words are that important, why can they still cause misunderstandings? Why is it this easy to alter the truth, to lie, with those words that are so essential? Why can't they truthfully express the thoughts and notions coursing through the mind?
No words can describe how it feels to perceive emotions, how it feels to care about another, how it feels to struggle with your own mentality. All that words can do is compare. Compare to something known for the person who receives them.
But although words cannot express these sensations, people still understand. A loving mother knows her child's needs without words. A loved one does not need to be told to know. Even a pet's love becomes obvious without any means of communication.
So as useful as words may seem and be, they will never be as truthful, as meaningful, as the purest conveyance of thoughts: emotions.