[A] form of social ostracism in which individuals, groups, or institutions face public backlash—often on social media—because of perceived objectionable behavior, statements, or values. Withdrawal of support often aims to deny or frustrate the expression of the called-out party’s beliefs or work.
To define it personally, cancel culture is the idea of removing someone from a pedestal of sorts due to something they have done, reflected, or stated. While it isn’t an inherently bad thing to strive to strike a person off the record for objectionable behaviour, cancel culture in itself has, in my own opinion, devolved somewhat — especially combined with the fact that the internet is immutable and knowledge is forever within it.