Who makes up the LGBT community? --What is the difference between discrimination, tolerance, and inclusion? --How do you make a change from the middle of an organization?

The LGBT (lesbian, gay, bisexual, and transgender) community is a highly diverse community that consists of an endless number of identities. Generally, the acronym "LGBT" is used as an umbrella term to define those who identify as not heterosexual and/or identify outside of the gender binary. "Queer" is another umbrella term that is commonly used to identify this community. The terminology used to define the LGBT community has evolved rapidly over the years. In the 1950s, the term “homophile” was used to describe those with same-sex attraction. In the 1960s, the term “sexual minority” was better known. In the 1970s, “gay” came to be commonly used. In the 1960s and 1970s, lesbians paved their way into the movement and its focus shifted to “gay and lesbian.” In an attempt to be as inclusive as possible, the acronym LGBTTQQIAAP2S (lesbian, gay, bisexual, transgender, queer, questioning, intersex, asexual, ally, pansexual, two-spirit) is sometimes used. As with any minority community, there are disputes within the LGBT community about who is LGBT. Furthermore, there is criticism of the use of acronyms. Some believe that the acronyms are confusing and alienate potential allies from understanding the community. Others believe that acronyms limit and confine identities. Furthermore, the community is so vast that each member tackles very different social stigma. For example, a masculine-presenting lesbian may experience housing discrimination. Meanwhile, a transgender woman may experience medical discrimination. This is even further complicated when compounding identities are considered. For example, a black gay man may experience different discrimination than a white gay man. Generally speaking, the LGBT community shares the experiences of housing discrimination, medical discrimination, street harassment, violence, and employment discrimination. LGBT people are incarcerated at a rate three times greater than the general population. Despite being a highly diverse community with so many different interests, the LGBT community shares these concerns.
Discrimination is defined by the United Nations Educational, Scientific, and Cultural Organization as

intentional or unintentional behavior for which there is no reasonable justification. Such behavior adversely affects specific individuals or groups on the basis of characteristics.

The LGBT community faces discrimination in many forms, including in housing, employment, and medical treatment. In 2016, one in four LGBT Americans reported experiencing some form of discrimination. 27% of transgender employees report having been fired or denied employment due to their identity. Discrimination has the harmful effect of impacting one’s mental health. LGBT youth are five times as likely as heterosexual youth to consider suicide. This is greatly linked to the discrimination the community faces.
Tolerance is a contentious topic among the LGBT community and their supporters. Generally, tolerance is the acceptance of one’s identity. However, many argue that the idea of tolerance suggests that there is still something inherently wrong with the identity in the first place. Activists argue that sexual identity is nothing to "tolerate." Rather, it is something to accept and understand.
Inclusion is the flip side of discrimination. While discrimination excludes the LGBT community, inclusion is its antithesis. There are many ways the LGBT community can be included in society. One monumental example is the recent passage of marriage equality on a federal level. Here, LGBT Americans have been included in the institution of marriage.
There are many strategies for changing the culture of an organization. It is important to have dialogue with peers about the desired change. The Society for Human Resource Management (linked below) suggests ten steps for driving a culture change. A simple way to be inclusive of LGBT people in your organization is to practice introducing yourself with your preferred pronouns.
https://www.shrm.org/hr-today/news/hr-magazine/1016/pages/how-to-change-your-organizational-culture.aspx