The development of a set of key technologies enabled the development of FreeSurfer, an array of image analysis tools designed to be automated, robust, accurate and relatively easy to use. This included automated geometric accurate topology correction (Fischl et al., 2001), surface-based inter-subject alignment (Fischl et al., 1999a, 1999b) and whole-brain segmentation (Fischl et al., 2002, 2004a). Although in many ways these still represent the core functionality of FreeSurfer, it has also evolved tremendously since that time. For example, we have recently adopted a liberal open source license that allows great freedom in the use of our source code (http://surfer.nmr.mgh.harvard.edu/fswiki). FreeSurfer is constantly being improved and extended, with our most recent release including tools for accurate cross-modal intra-subject registration (Greve and Fischl, 2009), combined volume and surface cross-subject registration (Postelnicu et al., 2009b), probabilistic estimation of cytoarchitectonic boundaries (Fischl et al., 2008), automated tractography (Yendiki et al., 2009), and longitudinal analysis (Reuter and Fischl, 2011; Reuter et al., 2010). It has been used to improve our understanding of an array of neurological disorders (Becker et al., 2008; Desikan et al.,
