DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome Assembly is the process of reconstructing the original DNA sequence from the fragment reads alone.

http://galaxyproject.github.io/training-material/topics/assembly/