An easy way to organize the data by groups of sequential numbers. This is very helpful for splitting up a large file into numerous smaller files. You can then create the smaller files by filtering for the row number per file.
For most DBAs, normalization is an understood concept, a bread and butter bit of knowledge. However, it is not at all unusual to review a database design by a development group for an OLTP (OnLine Transaction Processing) environment and find that the schema chosen is anything but properly normalized. This article by Brian Kelley will give you the core knowledge to data model.