A consent management platform is software that asks visitors for permission to set non-essential cookies, blocks trackers until that permission.
A cookie wall blocks access to a website until the visitor accepts cookies. EU regulators have largely rejected them: consent that is forced is not.
Legitimate interest is one of the GDPR's legal bases for processing personal data, covering uses that are necessary for a business purpose and do not.
Dark patterns are banner designs that push visitors toward accepting: a bright accept button with a hidden reject option, confusing wording, or extra.