So what's this about Google trampling over our online privacy again?The internet giant is changing its privacy policies and "terms of service" from March 1st, consolidating them across nearly all its myriad services. This will allow Google to pool all the data it collects about its users after they sign in.

Previously, the information about what you searched for in Google, watched on YouTube, looked up on Google Maps and mailed about in Gmail was separate. Now, it will be unified and cross-referenced.

Wait, it doesn't do that already?Nope. Google says this will make its search results more accurate for you, and its other services more personalised and tailored to your interests. According to Alma Whitten, Google's director of privacy for product and engineering, the changes mean "we'll treat you as a single user across all our products, which will mean a simpler, more intuitive Google experience". And make it easier to target ads at you.

Is this anything to do with that Google+ search brouhaha?Not directly. There was pushback last month when Google introduced Search Plus Your World, which rejigged its search results to prioritise results from the Google+ social network over Facebook and Twitter.

Wait, why is Google suddenly going all Mark Zuckerberg on us?Both moves can be seen as an attempt to keep up with Facebook in the great personal-data race – and, in effect, in the great internet-advertising race. There's no such thing as a free webmail service, search engine, browser, social network, streaming video service, online atlas or smartphone operating system. As the US blogger Matt Yglesias put it, "Once the basic business proposition is, 'This company will make the most amazing Web services available and give them away for free in order to sell you to advertisers', plummeting levels of privacy become inevitable."

What does this mean for me as a user?If you already have a Google user account and use Gmail and YouTube and search all the time, you might notice more refined search results, or better management of your contacts. If you're concerned about online privacy, well, maybe consider using some alternatives.

There are alternatives to Google?When did that happen? Microsoft has wasted no time in taking advantage of Google's move, taking out full-page ads in US newspapers this week reminding people it offers rival online services such as Bing search and Hotmail (yes, it still exists). It didn't pull any punches. "Every data point they collect and connect to you increases how valuable you are to an advertiser." Of course, if you're really concerned about advertisers knowing your every interest or desire, you can turn off personalised ads in your Google settings, which is nice.

What's Google's reaction to the negative reaction?It in turn is running ads to reinforce the positive aspects of the changes. "We're changing our Privacy Policy. Not your privacy controls." But the US Federal Trade Commission is scrutinising Google's every move, aware its huge search monopoly could easily lead to anti-competitive practices.

So is this the end of that Don't Be Evil rule?There's is no shortage of pundits claiming these changes are the very essence of evil, but the reality is somewhat more benign. But it's probably wise to be aware of how to manage your online privacy and decide for yourself whom to trust.