A more thorough explanation:

The hearsay rule is a legal rule that says you can't use statements made outside of court as evidence in court. This is because the person who made the statement isn't there to be questioned about it.

For example, if someone says "I saw John steal the money" outside of court, that statement would be hearsay if someone tried to use it as evidence in court. This is because the person who made the statement isn't there to be questioned about what they saw.

However, there are some exceptions to the hearsay rule. For example, if someone makes a statement about their current state of mind, like "I'm feeling really scared right now," that statement might be allowed in court because it's not being used to prove something that happened in the past.

Another exception is the business records exception. This means that records kept by a business, like receipts or invoices, might be allowed in court even if the person who made the record isn't there to testify about it.

It's important to follow the hearsay rule because it helps ensure that evidence presented in court is reliable and can be questioned by both sides.