What is the difference between linear and conformational epitopes? and why is this important?

Linear epitopes are epitopes that are located on the antigen in a linear fashion, while conformational epitopes are spread on the antigen, requiring a fold/3D structure of the antigen when the antibody binds this is important when you're analysing and detecting antibody-antigen reactions. e.g. in ELISA, mostly linear epitopes are used.