Hearsay can be a very complicated area, which can even trip up lawyers and judges, but generally speaking, hearsay is evidence that is based on the reports of others rather than the personal knowledge of a witness. Hearsay is not admissible in court. An example of hearsay would be having a witness at a trial say, "I heard from Joe’s mom that Joe was at the movies that night." In this case the witness has no personal knowledge that Joe actually was at the movies, he’s just repeating what someone told him. If it’s important to the case to have the word of Joe’s mother, the lawyer should get her in court, because then she can testify from personal knowledge.