There are as many answers to this question so it would seem, as there are communities in existence. Community can be a vague reference to people in general, or to a specific group, such as residents in a block of flats.
Being part of a community provides us with connection, belonging, self worth, opportunity to contribute, support / help others, and take co-responsibility for something, all of which gives meaning to our lives. It is easy to see why community is important to us, many of our primary human needs are included in the list above.
However, in our modern day world, huge numbers of people are finding themselves isolated, depressed, apathetic, lacking in self esteem, and often, disbelieving of their own worthiness.