TOR is one of the "free" VPN's out there.  You should be aware that the free sites don't have any reliable revenue stream which can be used to operate their business.  Consequently, they create revenue off of your information by selling your email address, and mining information about which sites you visit, to other companies, so the PRIVACY you THINK you're getting is somewhat illusory.  Paid VPN's have a revenue stream from user fees, just like TER operates.  This allows them to address problems, perform maintenance, and give faster and better service than the freebies.  

 
Some of the paid sites are running specials right now for as little as $7 a month, and your privacy is not compromised, nor is your information sold to create revenue.  Before signing up with a "free" VPN, I encourage everyone to read the privacy statement and take notice of the various "limitations."  Within the scope of the limitations is how they are going to make their money off of you to compensate for the lack of user fees.  You just have to decide if a lack of complete privacy is worth saving $7 a month.  At that price, it was a no-brainer for me.

Your understanding is indeed limited. Tor is a browser and not a VPN and does not require an email address to access it nor to use it The TOR  browser was originally designed to be used by people in countries where accessing certain sites is illegal and you can be imprisoned or worse. Although nothing is truly anonymous online, for the purpose of gaining access to TER, the TOR browser is a great option that is free and provides anonymity.