The Internet is free and we all demand that it remain so, but nothing is really free. One way that money is garnered is by companies monitoring the places you visit on the Internet and then creating a profile of you, by name, so that advertisements can be sent your way.
There is a way to stop this.
Select Safari → Preferences → Advanced and put a check in the box next to “Show Develop menu in menu bar”.
The word Develop will now appear as an additional item in the Safari Menu Bar. Select it and you will see several items. Most of them will be of no interest because this tool is really designed for app developers, but the one you want to activate is “Send Do Not Track HTTP Header”.
This can make a big difference in protecting your privacy.