Junk DNA is non-coding DNA it does not code for protein.

junk DNA

No - only a small part of human DNA is coding DNA. About 3% of DNA is genes. These are the sequences that code for a functional unit (like protein).

Coding DNA or exons are varying among individuals. But non-coding DNA doesn't vary among individuals and they don't carry information about gene expression patterns. Therefore, non-coding DNA is used in forensic analyses.

No - only the parts of DNA that code for a functional product, like protein, are considered coding DNA. This is only a small amount of DNA - about 3% in humans.