In the context of biogeography, the word 'Nestedness' indicates a situation where species occurring at the site of interest are always present in a more species-rich site, whereas species absent from the site of interest never occur in a less species-rich one. Thus, if species occurrences are arranged in a species-area matrix, and the rows and columns of that matrix are ordered according to their respective totals, the matrix is nested if most of its presences are concentrated in the upper left triangle (Ulrich et al. 2009). NeD makes it possible to easily compute nestedness using the most robust available combination of measures and null models. NeD is implemented as a dynamic web system using the open source scripting language Python (van Rossum and de Boer 1991) and Django web framework (Holovaty and Kaplan-Moss 2007). This means that you can use NeD online, without need to install anything on your PC. Additionally, a static version of the software is available for download. With static NeD you can automatize multiple (“batch”) analyses. Otherwise, there are no differences between online and static NeD.
Ref: Strona, G., Galli, P., Seveso, D., Montano, S. & Fattorini, S. (2014). Nestedness for Dummies (NeD): a user friendly web interface for exploratory nestedness analysis. Journal of Statistical Software, 59: Code Snippet 3: 1-9. (IF: 4.910) (IF2013: 3.801; Q1 Statistics & Probability)