Coming out of the closet, or simply coming out, is a figure of speech used to describe the process of lesbian, gay, bisexual, and transgender people disclosing to themselves and to others their sexual orientation and/or gender identity. It has been described as a ‘rite of passage’, a ‘liberation’ or ’emancipation from oppression’, and a means toward feeling gay pride instead of shame and social stigma.  from Wikipedia
We live in a heterosexist society. This means that our collective thoughts and behaviours are sponsored by the inherent assumption that everyone is or should be heterosexual. Some people will feel uncomfortable observing anything that contradicts this assumption. This discomfort is called homophobia. 
The young person just emerging into adulthood who has begun to realize that he is different, and the difference is not approved of, finds acceptance of self particularly difficult.
from Homophobia: The Fear Behind The Hatred An essay on the origin and nature of homophobia by Scott Bidstrup
In coming out, each individual has to deal with his or her own internalized homophobia. This is true for those who grow up here in the West Island. We’re not exempt from the issues of sexual orientation and gender identity. Children understand from an early age that those who are gay are different and are often subjected to anti-gay bias – disapproval, discrimination and prejudice. It’s not easy to reveal your true self when you know that it will bring that focus of attention and inherent prejudice upon yourself. And coming out is a continuous process that happens throughout life; the reality is that every time you encounter new people, you’ll encounter homophobia again.
Parents, family members and close friends also experience a coming-out process of their own, a part of which is dealing with their own homophobia. Since homophobia is based on the lack of understanding about gay issues, and fear of what we don’t understand, meeting with other people to talk and learn about gay issues will help to provide answers and understanding. There is more information pertinent to the concerns of parents on the Parents page.
PFLAG Canada, a support group for Parents and Friends of Lesbians and Gays, has a lot of very good information about coming out available through their website at www.pflag.ca. But, as one of their documents points out, “There is a great deal of online information available to parents of gay, lesbian and bisexual children, but reading does not provide the same peace-of-mind as sharing your concerns with another parent, especially one who has faced a similar situation.” To that end, the main purpose of our Youth Centre is to be a support community for you as you come out, and also for your families and friends, that will allow you the opportunity to meet and talk and learn together.
While coming-out is an important part of self-acceptance, there’s no one right or wrong way to do it, no right or wrong time to do it, so remember that you’re in charge – you decide who to confide in, when to do it, where to do it and how. Don’t be forced by external factors or other people. When and how you decide to come out is a PERSONAL decision. Just know that we’re here to reach out and support you, not to convince you to come out.
And, if you’re concerned about a family member, loved one or colleague, it is important to let the individual take their time, don’t force them to acknowledge what they may not yet be ready to accept themselves – in other words, be careful not to “out” someone else.  from pflagcanada.ca
The Children’s Aid Society of Toronto has put together an excellent, informative document about coming out called Out and Proud – www.torontocas.ca/…/outandproudcomingout.pdf
One small excerpt:
Reasons to come out
No more lies
Keeping up the complicated lies that you may have to tell in order to keep your sexuality a secret takes a lot of energy and wears away at your self-confidence. It can feel like a huge relief once the secret is out.
You find real support for who you are
You will learn who can accept the real you, not some ficticious person you have had to invent. This will deepen your friendships. The people who cannot accept you will be replace by those who do.
Possibility of acceptance
Even though families have mixed reactions, many come to a place of acceptance. Once this process starts, many LGBT people say they feel a big sense of relief that they have stopped lying to the people they love. It can also begin a deeper sense of trust with others and with yourself.
You begin to feel like you fit in
Although most LGBT people always feel some degree of being an outsider, when you are comfortable being out, it will help you be more genuine in your relationships. You begin to see that everyone is different, that it’s the differences that make life interesting.