Descriptivism vs. Prescriptivism
Descriptivists: study how words are used in society by the people actually saying them and then records that meaning describing the common usage of the word.
Prescriptivists: Follow the definition generally understood to be correct as recorded in a dictionary or other scholarly source and apply that meaning onto the usage.
So for example if you were to ask "Can I go to the Bathroom," a prescriptivist might say, "I don't know, can you?" as under a traditional definition of 'can' it describes capability rather than permission, where as a descriptivist would say "Yes" because they understand when people ask to use the bathroom, they need to use the bathroom, they aren't questioning their own biological functions.
In terms of queerness, it is essential to view any label from a descriptivist lens as meanings are constantly changing, evolving, and growing to fit speaker's needs. The word 'Lesbian' might be commonly understood to describe a woman who loves women, but as the queer community expands and diversifies, that simple definition might no longer apply to everyone who uses that word, such as nonbinary people or trans masc men who feel as if 'lesbian' is still the best way to explain how they love others.
Queerness is all about meeting people where they're at, forming community around labels, and being open and curious about things you don't initially understand. Remember to maintain a descriptivist view of learning and understanding when studying queerness and be ready to leave your preconceived notions at the door.