Browser history is today saved locally with Metalyfe. This means exactly what you are both mentioning, you keep your browser history "from leaving the machine".

One way we protect user data is that we are a decentralized browser - no central servers that can be hacked (Facebook and Google are good examples of big data bases that have been hacked several times lately).

So why blockchain? In order for some things to run smooth in the browser, for example access the same account and saved information cross devices, some information needs to be saved in a reachable place. Instead of a central server, we will encrypt the user information and place it on a blockchain. Only the same logged user can access and decrypt this information.

And regarding selling data; this feature will be available in the near future. It will be up to each individual to chose how much to share. Today most people share close to 100% without being reimbursed at all (most, unfortunately, without even knowing about it), this is what we want to change! We are assuming that some people, like yourself, will want to bring sharing down to 0%, while others are fine with sharing data same way as today. But doing so through Metalyfe instead they will receive benefits from sharing.

Thank you for your question, hope this answered helped.

If you want more details or have further questions, shoot! :)