The phrase "heart of the matter" refers to the crux or essence of a particular issue, situation or problem. Synonyms for this expression include the "nub" of the matter, the "core" of the problem or the "meat" of an issue. Other phrases commonly used to convey a similar meaning include the "root" of the problem, the "bottom line" or the "real issue" at hand. It is important to identify the heart of the matter when trying to solve problems as this will enable individuals to address the underlying causes rather than simply treating the symptoms.