Evernote tags == Outlook Categories == GMail Labels. However Outlook's Categories and GMail's Labels are not folder systems. Both Outlook and GMail have separate folder systems, so you can mix'n'match, just like with Evernote (though Evernote's notebooks have the also-well-known properties of being one level deep, albeit organizable in stacks). Tags, Labels and Categories all function like adjectives. Folders are more familiar, it's true, but not necessarily simpler, particularly when you try to scale them to larger systems of disparate items. My old example of classifying a red ball is a case in point; do I put it in the 'Red' folder or the 'Spherical' folder or the 'Toy' folder? It's not something that has a single easy answer, whereas it's pretty simple to describe it using tags. And tags are also quite familiar, if you understand them as simple adjectives or labels. I'd guess that most people learn adjectives before they learn strict hierarchies. I think I have to disagree with you slightly on the folder systems in Outlook and Gmail. If you look at that structure on your screen, they both look and operate exactly as your normal folder system on your hard drive. I can even put folders inside of other folders in both these programs. Specifically it is this appearance and familiarity that makes them so simple to use. And in spite of the differences in their terminology, my Outlook folders and sub-folders sync perfectly with Gmail's labels. Outlook then has additional CATEGORIES that you can use, and these are more similar to Evernote's Tags. Evernote's combination of tags and notebooks work well together, but when many users are involved who all need access to the same notebook, how can more tagging help? We tried it all, and tagging is not the answer. A folder structure may not always be simpler, but SHARED folders (notebooks) are the only thing that work across many desktops and mobile smartphones. Under that scenario, tagging is not simpler at all. Unlimited notebooks is the answer for my company, and probably any other companies who need what we need. I am not bashing Evernote. We love it, and it was working well for us. I just ran out of notebooks.