The essence of Google’s changes are that any private data now collected by one Google service can be shared with all of its other services, such as Gmail, YouTube and Blogger. So, any browsing data or web history which Google gathers when you’re signed in to your Google account can now be shared across all of their other sites. These are all sites owned by Google, but to avoid this, you can simply not log in to your Google account, and Google will just store your web data activity anonymously.
Google says that this is to offer better targeted advertising to users, and will enable it to tailor its search results more effectively. Google makes a huge amount of money from advertising, so the more information it has about you stored centrally and collected from all its different sites, the more accurately it can target you. This is good news for people who do Google pay-per-click advertising. The changes also brought together documents for more than 60 different sets of individual sites that are owned by Google into one single policy document covering all of the sites, simplifying its policies.