Exactly...and then those are interesting in _how_ they became the dominant player. Did they offer something the predecessor didn't, etc. Why MS succeeded can be argued around various points re: digital (re: CP/M), the boom of compatibility issues with the 808x machines (back in the DOS days and the proliferation of white box machines (aka IBM compatibles)), and the failure of OS/2 (I'm sure it's more complex than this, but.... Google succeeded as it was (imo) largely faster and more complete than the akebono preliminary as well as the adoption/evolution of the goto.com advertising paradigm. As to how facebook beat out myspace? I haven't heard convincing arguments that are definitive; however, they appear to have placed more of a focus on social aspects than myspace did (and they were less "geocities-like").