Give me a summary of why an abstract is useful in academic literature?

An abstract is useful in academic research because it conveys the complex research in a concise way by acting as a stand-alone summary. Therefore, it is usually used by many organizations as a base for selecting research. Moreover, abstracts are usually provided free of charge by many bibliographic databases which makes the research works more accessible. In addition, researchers can understand if the work is relevant to their research just by reading the abstract.