Probable cause is a legal standard where there’s enough evidence to reasonably believe a crime has been committed or that specific evidence related to a crime can be found in a particular place. It’s more than a hunch but less than proof beyond a reasonable doubt—think of it as a “reasonable belief” based on facts and circumstances. For example, if a police officer sees someone weaving dangerously on the road and smells alcohol during a stop, that’s probable cause for a DUI investigation. It’s rooted in the Fourth Amendment of the U.S. Constitution, balancing individual rights with law enforcement’s need to act. Courts often look at the totality of circumstances to determine if it exists, like for issuing search warrants or making arrests.