An AD trailer is a type of advertisement that is typically shown before a movie in a theater. It is usually a short video clip that promotes a product or service. The term 'AD trailer' is an acronym for 'advertising trailer.' LIB and HOC are two common abbreviations used in the advertising industry. LIB stands for 'low impact branding, ' which is a type of advertising that does not require a large budget. HOC stands for 'high-octane creative, ' which is a type of advertising that requires a larger budget and more creative input.