Can anything you do online remain truly private in this day and age? One out of every eight people in the world has a Facebook account that they fill with personal information. People tweet details about their daily lives. And it seems that every site we visit online wants to install a cookie to track our online progress.

But just because we live in a culture where privacy is often willingly surrendered, you shouldn't give up and give away your information to just anyone. Past problems with these five corporate giants should definitely make you think twice.

Facebook

Facebook is already using the plethora of information it has gathered about you to deliver ads tailored to your specific tastes. If you use applications within Facebook, those third parties have access to all your personal information, as well. And of course, should your account ever be hacked, you risk a complete stranger's learning and being able to exploit every intimate detail about you, including your address and phone number.

The good news is that Facebook has a number of tools to manage privacy settings, offering you control over who sees what information you post. But even this may not keep you safe. Remember that embarrassing picture of yourself that you deleted off Facebook three years ago? A recent study shows that it likely still exists — Facebook never deleted it. This example is far from the first privacy misstep Facebook made, and it surely won't be the last.

And here's another scary anti-privacy trend related to Facebook: More and more job applicants are being asked to surrender their Facebook passwords by prospective employers. It's not just job searchers who need to fear for their privacy, either — if your children play in college athletics, they may have already been forced to give a school official total access to their Facebook account as a prerequisite to playing.

2. Sony

Things began to go south for Sony when its PlayStation Network (PSN) was hacked in April 2011. That breach exposed millions of names, addresses, usernames, and passwords, exposing PSN users to the threat of identity theft. It took Sony a full month to assess the damage and bring the PSN back online.

But the first attack was merely the tip of Sony's privacy iceberg. The PSN was brought down almost immediately after it went back online in May 2011 by a new security exploit. A few days after that, Sony websites in Thailand and Japan were hacked, with the bad guys stealing about $1,200 in customer funds. And in October 2011, an estimated 93,000 PSN accounts were breached — a third black eye for a company that had yet to heal from its previous two.

Apple

Few companies have impacted the way we view and use technology over the last decade quite the way Apple has. And perhaps it's precisely because so many of us rely on iPads and iPhones that this next revelation is so devastating. Until last month, Apple readily allowed third-party app developers access to your phone's address book without your knowledge. Some apps even gave hackers a back door into your phone, albeit unintentionally.

News of these privacy violations broke when it was revealed that the increasingly popular social networking app Path was not only accessing users' contacts but uploading the contacts to a private server. The revelation was enough to draw congressional attention, with Reps. Henry Waxman (D-CA) and G.K. Butterfield (D-NC) demanding Apple reveal which apps have access to this info and why it allows app makers to grab address book data without telling us.

Apple quickly responded to Congress that apps such as Path were in violation of its guidelines and that it would be implementing a software patch to prevent apps from accessing address books without our knowledge in the future. Still, it's chilling that Apple let the practice go on long enough for one iOS app developer to brag that he had access to Bill Gates's and Mark Zuckerberg's cell phone numbers.

4. Your phone carrier

Given the strict federal rules against wiretapping, communications privacy, and computer fraud, you might find it downright shocking to learn that your wireless carrier might have full access to every single keystroke you make on your mobile device. But that might be exactly the case, all thanks to a little-known company in Mountain View, California, named Carrier IQ.

Carrier IQ's software, which bills itself as a tool for mobile providers to help assist customers during support calls, was preinstalled on many smartphones currently in use without customers' knowledge. The company insisted for the longest time that its software did not have the ability to log browser data and text message contents, but an intrepid Android blogger posted a YouTube video showing the software doing exactly that.

Is your phone saddled with Carrier IQ spyware? It's possible — at least if you're using an AT&T, a Sprint, or a T-Mobile phone. Thankfully, Carrier IQ's days of spying may be over. Apple, one of the largest suppliers of smartphones, stopped supporting the Carrier IQ service when iOS 5 was released last year. Further, Congress is moving aggressively to stop the practice from ever happening again, and a number of states have filed civil and criminal suits against the company.

Google

We want to love Google, we really do. The company does a lot of social good, from helping save the Great Barrier Reef to trying to engineer the future of driverless cars. But even though it pains us to do so, we have to include Google on our list because of the most recent changes to the company's privacy policy.

On March 1, all sites within the Google network began sharing your personal information with each other. If you watch a video for a political candidate on YouTube, Google might start serving you ads asking you to make a donation to candidates with similar political views. Every single search you make on Google adds to its level of knowledge about you — the company knows if you're pregnant, if you suffer from heartburn, and even if you're a smoker.

Sure, we trust that no summer intern at Google HQ rifles through filing cabinets filled to the brim with your most embarrassing web searches. But the simple fact that this massive treasure trove of information exists somewhere means that the potential for this information to fall into the wrong hands exists. Given how influential Google is to the web experience and given the fact that you can't actually opt out from Google's new policy, it's hard to protect your privacy from the company. Still, you're not entirely helpless — you can easily erase your Google history and stop the company from collecting information about you in the future.

Play it smart

As technology becomes a bigger and bigger part of our social lives, it's likely the trend of voluntarily surrendering our privacy will continue. But that doesn't mean you can't be smart about whom you give information to and how much you share. Familiarize yourself with the privacy policies for your favorite sites and businesses, and opt out of having your data collected. If you have kids, be sure to educate them about the dangers of sharing highly personal information with strangers online.

[Image credit: Robert Scoble]

This article was written by Fox Van Allen and originally appeared on Tecca