Circumstantial evidence is best explained by saying what it is not - it is not direct evidence from a witness who saw or heard something. Circumstantial evidence is a fact that can be used to infer another fact.
Indirect evidence that implies something occurred but doesn't directly prove it; proof of one or more facts from which one can find another fact; proof of a chain of facts and circumstances indicating that the person is either guilty or not guilty.
E.g., If a man accused of embezzling money from his company had made several big-ticket purchases in cash around the time of the alleged embezzlement, that would be circumstantial evidence that he had stolen the money. The law makes no distinction between the weight given to either direct or circumstantial evidence.
E.g., X is suing his wife, Y, for a divorce, claiming she is having an affair with Z. Z's fingerprints are found on a book in X and Y's bedroom. A judge or jury may infer that Z was in the bedroom. The fingerprints are circumstantial evidence of Z's presence in the bedroom. Circumstantial evidence is usually not as good as direct evidence (an eyewitness saw Z in the bedroom) because it is easy to make the wrong inference
Y may have loaned Z the book and then carried it back to the bedroom herself after getting it back.
Circumstantial evidence is generally admissible in court unless the connection between the fact and the inference is too weak to be of help in deciding the case. Many convictions for various crimes have rested largely on circumstantial evidence.
The particulars which accompany a fact.
The facts proved are either possible or impossible, ordinary and probable, or extraordinary and improbable, recent or ancient; they may have happened near us or afar off; they are public or private, permanent or transitory, clear and simple or complicated; they are always accompanied by circumstances which more or less influence the mind in forming a judgment. And in some instances these circumstances assume the character of irresistible evidence; where, for example, a woman was found dead in a room with every mark of having met with a violent death, the presence of another person at the scene of action was made manifest by the bloody mark of a left hand visible on her left arm.
These points ought to be carefully examined in order to form a correct opinion. The first question ought to be; is the fact possible? If so, are there any circumstances which render it impossible? If the facts are impossible, the witness ought not to be credited. If, for example, a man should swear that he saw the deceased shoot himself with his own pistol and upon an examination of the ball which killed him it should be found too large to enter into the pistol, the witness ought not to be credited. Or if one should swear that another had been guilty of an impossible crime.