The expression sexual orientation refers to a sexual interest in people, objects or activities. In terms of partner selection, women can sexually be interested in men (heterosexual), in women (homosexual) or both men and women (bisexual). Another form of sexual attraction is towards all gender varieties (pansexual). There is also a general lack of sexual interest (asexual). [1]

Other possible forms are sexual interest in animals (zoophilia), objects (fetishism) as well as certain sexual activities such as exhibitionism, sadism, masochism etc. [1]

The abbreviation LGBT stands for Lesbian, Gay, Bisexual and Transgender and has been in normal speech since the 1990's. It used to be a political movement which tried to show the variety of sexual orientation and gender identities and support the rights of LGBT's. [2]

According to various studies, the number of LGBT is ranging between 1.2 and 5.6% of the entire population. In the US, for instance, 3.5% are LGBT, while 0.3% are transgender. [4]

At scientific level, queer studies and gender studies address gender roles, identity and sexuality and how the topics are interlinked. Queer theory, which was mainly coined by Michael Focault and Judith Butler, questions social norms concerning sexuality and relationships [HETEROSEXUALITY], as well as the binarity concept in which man and woman are the two main gender roles. [5]

Currently, new varieties of sexual orientation and different terms are emerging such as demisexual, sapiosexual, polyamorous, kink, heteroflexible, aromantic... This allows people to clearly communicate their individual wishes concerning relationship and intimacy, to reconsider old patterns and to change role models.

Further Links:
Sexual Identities: Prefixes, sexplanations, 2015 (YouTube)
"Ist das jetzt sapiosexuelles Begehren?", Wenke Husmann, 2015 (ZEITmagazin)
On Sexual Orientation with Hannah, Ze, Tyler and Meg, 2013 (YouTube)
Enumeration of different sexualities and identities (Queer Lexikon)