In simple words, sexual orientation stands for sexual identity of people in relation to the gender to which they are attracted sexually, leading to people being categorized as being heterosexual, homosexual, or bisexual.

Currently, sexual orientation or sexual preference is being seen under four categories, namely, heterosexuality, homosexuality, bisexuality and asexuality. The last category is that of people who lack sexual attraction to others.

The term 'sexual orientation' took the fancy of psychologists and social scientists, when in 1948, the book "Sexual Behavior in the Human Male" by Alfred Kinsey hit the market. He had proposed that 'male sexual orientation lies on a continuum between exclusively homosexual to exclusively heterosexual'.

Another word was coined for homosexuals in 1950 by Harry Hay founded Mattachine Foundation - one of the first gay rights group in the United States - which was 'homophile' - considered less derogatory and focused on sexual activity preference.

Currently, the American Psychological Association's description of sexual orientation is being viewed as 'a person's sense of identity based on those (sexual) attractions, related behaviors, and membership in a community of others who share those attractions'.

Thus, it can been seen that three terms, sexual attraction, sexual preference and sexual orientation, overlaps and are seen as synonyms but the last has gained currency in the research literature in social sciences and humanities.

However, scientists theorize that sexual orientation is caused by a complex interplay of genetic, hormonal, and environmental influences, but the research is yet inclusive. Researchers do believe that sexual orientation ranges along a continuum, ranging from exclusive attraction to the opposite sex to exclusive attraction to the same sex.

Subscribing for view point that sexual orientation ranges along a continuum, it was in 2011, the United Nations Human Rights Council passed its first resolution recognizing LGBT rights, which was followed up with a report from the UN Human Rights Commission documenting violations of the rights of LGBT people, including hate crime, criminalization of homosexuality, and discrimination. The latest available statistics of March 2017 indicate that 23 countries recognize same-sex marriage.

Despite all this, Human Rights Watch (RHW) that works for LGBT peoples' rights, feels, "People around the world face violence and inequality - and sometimes torture, even execution - because of who they love, how they look, or who they are. Sexual orientation and gender identity are integral aspects of our selves and should never lead to discrimination or abuse." Keeping this view RHW advocate for laws and policies that will protect everyone’s dignity and create a world where all people can enjoy their rights fully.