It’s hard to imagine that just nine years have passed since the first video was uploaded to what is now the world’s most popular video sharing site.

It was April 23, 2005 when the very first video, entitled, “Me at the zoo” was uploaded to YouTube. It featured co-founder Jawed Karim talking about elephant trunks at the San Diego Zoo.

Since then YouTube has come a long way. It’s the third most visited site on the web and in recent years the service has migrated from the PC to mobile devices and even home theatre systems.

Here are some of the highs – and lows from the last nine years.

With close to two billion views, Psy’s 2012 “Gangnam Style” is the most viewed YouTube video of all time. While his follow-up, “Gentleman,” hasn’t been nearly as successful, it’s nonetheless garnered more than 667 million views.

Before Gangam Style, Justin Bieber’s “Baby” featuring Ludacris was the most viewed YouTube video ever. The 2010 upload still sits in the number two spot, with over one billion views to date. The site is also credited with helping Bieber explode from anonymity to world superstardom after a U.S. talent manager spotted the Stratford native online.

A number of other artists – including Jennifer Lopez, Lady gaga and Miley Cyrus – take up most of the other spots in the top ten most viewed videos.

In fact, the only spot not occupied by a music video belongs to 2007’s “Charlie Bit My Finger – Again!” The video features a British baby biting the finger of his brother, who wavers between pain and amused laughter.

Chanteuse Susan Boyle is another British YouTube sensation. The “Britain’s Got Talent” contestant shot to worldwide fame when her stunning performance in front of dumbfounded judges was uploaded to the site. She has since released several albums.

Other YouTube phenomena from over the years include a video of a child high on anaesthetics after a visit to the dentist, a video of a teen crying and ranting for the media to leave Britney Spears alone and a book of cat pictures narrated over by a little girl.

However music continues to dominate the site in terms of popular videos, especially odd or quirky ones. In 2008, Rick Astley's 1987 hit “Never Gonna Give You Up” spread like wildfire when jokesters started sending out emails with fake links that directed to the video.

Norwegian comedy duo Ylvis also made international headlines last year with their bizarre video, “The Fox (What Does the Fox Say?)” went viral.

Darker side

While the majority of YouTube content is light-hearted, the site has also shown a darker side.

British Columbia teen Amanda Todd used the site to post a video detailing her torment by bullies before she took her own life in October 2012.

The site has also become a popular place to post videos detailing purported injustices – sometimes even fatal incidents.

In July 2013, YouTube video surfaced showing officers engaging 18-year-old Sammy Yatim aboard a Toronto streetcar. Yatim died after he was shot, and then tasered by police. Footage of the incident captured by bystanders at the scene led to a public outcry, as well as second-degree murder charges against one of the officers involved. The charge has not been proven in court.

Plenty of footage also made its way to YouTube after the G-20 riots in Toronto in 2010. While most of the footage merely stirred popular opinion, last year one of the officers depicted beating protester Adam Nobody was convicted of assault.

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