No fixed essences beneath language. What counts as real is produced by discourse and power.
There is no view from outside. Study how truths are made and what they exclude.
How is this truth produced?
Key thinkers: Michel Foucault, Jacques Derrida, Gilles Deleuze
The longer story
Post-structuralism is suspicious of anything presented as fixed, natural or obvious. Meaning is not anchored to things; it is produced within language and shifts as language is used. Foucault showed how what counts as true, sane or normal in a period is the product of its institutions and discourses. Derrida showed how texts undo their own apparent certainties.
For a researcher the questions change. Not "what is the truth about this?" but "how did this come to count as true, who is authorised to say so, and what had to be excluded?" It is widely used across art theory, film, literature and gender studies. Few of its key figures accepted the label.