This is generally done for the purpose of taking the short shredded sequences and reapplying various analysis and bioinformatic techniques.
Being able to cut DNA samples and then run them through gel electrophoresis to study each strand in order to help find cures for diseases or illnesses is also another purpose.
Clustered regularly interspaces short palindromic repeats(CRISPR) - Cas9 allows genetic material to be either altered, removed or added at specific locations.
She discovered that DNA exists in species by taking multiple x-rays until she found an "X" looking diagram.
This is because the human DNA strand is very complex compared to an organism like a fruit fly, which has much simpler genes.