Late Bloomer is commonly used to refer to young children who develop skills such as language, reading, or social interaction later than others of their age.
The Theory of Factual Evidence states that theories can be proven true if a sufficient amount of factual evidence is provided. All ways of proof involve the assumption that this theory is true. Despite the importance of this theory (without it, nothing could be proven), it has yet to be proven correct.
Documentary evidence is often a kind of real evidence, as for example where a contract is offered to prove its terms. When a document is used this way it is authenticated the same way as any other real evidence--by a witness who identifies it or, less commonly, by witnesses who establish a chain of custody for it.