Loading pictures from your latest birthday party onto Facebook may be a good way to share the evening's memories with family and friends, but Canada's Privacy Commissioner warns that such a decision could also have negative personal and professional ramifications that last for years.

In her annual report to Parliament, Privacy Commissioner Jennifer Stoddart says many Canadians have lost their jobs, missed out on professional or academic opportunities or been suspended from school over online correspondence they mistakenly believed was private, such as wall posts on social networking sites.

So she's urging Canadians, particularly young people who live much of their lives online, to think twice about what they post on the Internet in an effort to secure their own privacy.

"Many young people are choosing to open their lives in ways their parents would have thought impossible and their grandparents unthinkable. Their lives play out on a public stage of their own design as they strive for visibility, connectedness and knowledge," Stoddart said Tuesday in a message attached to her report.

"Such openness can lead to greater creativity, literacy, networking and social engagement. But putting so much of their personal information out into the open can also ... leave an enduring trail of embarrassing moments that could haunt them in future."

The Commissioner's report on the Personal Information Protection and Electronic Documents Act, which was tabled Tuesday, includes a great deal of analysis on youth privacy issues and the social networking phenomenon.

Stoddart has made such issues a focus of her recent work. Earlier this year, she completed an investigation into Facebook's privacy policies, which spurred the company to make a series of changes to its operations.

In late August, Facebook announced that it would retrofit its website with new controls that would limit the personal information that third-party developers who build applications -- such as games and quizzes -- could access.

It also said it would permanently delete personal information of Facebook users who have deactivated their accounts.

Â鶹´«Ã½' Rosemary Thompson said the privacy commissioner considers social networking sites "a revolution in communications" that young people must approach with caution.

"This is a fascinating report, because what Jennifer Stoddart is saying, specifically to young Canadians, is watch out," Thompson told Â鶹´«Ã½ Channel on Tuesday in an interview from Ottawa. "When you post something to Facebook or Twitter or any of these social networking sites, it's up there forever potentially, and you can't change what's up there."

Stoddart is so concerned about the relationship between youths and the Internet that she has made online youth privacy a key priority.

She has developed a number of communications materials, including a website, www.youthprivacy.ca, that encourages young people to "Think Before You Click."

"Youth are the segment of the population most likely to embrace technology, yet some seem unmoved by the impact on their privacy. Or perhaps they're just not fully aware of the potential risks," Stoddard said.

"As Canada's privacy guardian, it is our role to create awareness of privacy risks, show people how to address those risks, and make it easy for them to make informed decisions."

The annual report also includes information about complaints the Commissioner's Office received and investigated in 2008.

The OPC received 422 complaints in 2008, up from 350 complaints in 2007.