Queer theory is characterized by whatever is at odds with the dominant or norm society identifies itself as. There is nothing the queer theory particularly pertains to. It can be seen as an identity without an spirit. Near the 20th century, the word queer was first used to mean 'homosexual.' Depending on the context the term can be offensive, positive, or it is rarely used.
Queer theory emerged out of queer liberation movement and critical Feminist and LGBT. One of the theorists, Michael Foucault focused on the History of Sexuality which led to his discovery of the key elements the postmodernist era influenced the development of queer theory. Over the years the (LGBTQ) Lesbian Gay Bisexual Transgender Queer population has adopted the term 'queer' and made it their own. Instead of using the term gay or homosexual they often use queer. Today, we are seeing the use of the word queer used more widely as the world has started to become a little more accepting of LGBT community itself.
When looking at queer theory it is essential to look at the range of critical theories including feminist theory and critical race theory that scrutinize social and cultural spheres. When working in a community that may have LGBT population present. It is important to understand and recognize the terms which have impacted the community at large. Not all individuals who identify as LGBT are okay with the term queer. It depends on the context that the term is used in and the values the particular community upholds with respect.