Scrivener. It's biggest advantage over something like Microsoft Word is that a Scrivener project is basically a custom file system for your manuscript, making i

Scrivener. It's biggest advantage over something like Microsoft Word is that a Scrivener project is basically a custom file system for your manuscript, making it incredibly easy to keep chapters and sections in separate files (for speed, focus, navigation and alternate drafts) and combine them seamlessly when necessary. Word .DOCs are sluggish to navigate when they get long, tempting to get sidetracked when you're supposed to be fixing a specific chapter, and don't provide a convenient place to stash meta-data (notes, outlines, scrap, alternate drafts, etc.)