Evidence includes testimony and/or documents and/or forensics that are relevant to the prosecution or the defense in a particular case.
Testimonial evidence may be offered by an eye witnesses. That is, someone who saw or heard something that tends to prove a point relevant to the prosecution or defense. Testimonial evidence may be offered by the alleged victim or an expert or a police officer who investigated the case.
Documentary Evidence can be almost any document that you can think of. However, it must be authenticated which means that someone from whatever business or institution that created the document must qualify as the person responsible for maintaining the file for said document. Also, the document must be something that is relied upon in the normal course of business of whatever entity has produced it. Any document that is created for use at trial is not admissible.
Forensic evidence includes DNA, fingerprints, footprints, hair, etc. Forensic evidence is the stuff that needs to be described as to its identity and importance by some kind of expert. Forensic stuff is not evidence unless someone who has been properly qualified can talk about what it is and how it is of relevance to the case.
The "expert" who testifies about the forensic evidence must be carefully cross examined with the intent to impeach. Many so-called experts are just a bunch of hot air.
What are their credentials? How long employed? Who is paying them for their work? Who is paying them for their testimony? How many times have they testified for the defense? What have they published? What do they read? There are lots and lots of ways to de-value a so-called expert's testimony.
The prosecution's evidence should always be treated with skepticism by the defense. Even if it gets admitted, the defense can still attack its value.