Then: Yelp started as a more complicated version of its current iteration. Back in 2004 when it was founded, Yelp created an email system so users could contact others to recommend local businesses.

Now: They've cut out the noise, and Yelp now lets users look for reviews of businesses themselves.

Then: Groupon started as ThePoint.com. Launched in November 2007, the site let you start campaigns asking people to give money or do something as a group — but only once a "tipping point" of people agree to participate.

Now: Groupon is a website that lets you pick from its marketplace of deals. You can book a vacation on Groupon Getaways or get a restaurant reservation in your city for a steal. Groupon went public in November 2011.

Then: Flickr used to be Game Neverending, a massively multiplayer online roleplaying game that ran from 2002-2004.

Now: Flickr is one of the go-to sites for sharing photos online, popular among amateur and professional photographers. It sold to Yahoo in 2007 for $40 million.

Then: When Intel was getting off the ground, it primarily made memory chips.

Now: The company currently specializes in producing the microprocessors that run most personal computers.

Then: YouTube was a video dating site!

Now: YouTube's the go-to location for internet videos. YouTube is creating a new generation of media stars, who are worth millions. Now, YouTube's experimenting with a subscription service.

Then: Founded in Finland in 1865, Nokia was a rubber company that made galoshes and other products.

Now: It's a communications company that makes their name with cellphones. Nokia has a $28 billion market cap.

Then: When Google bought Android in 2005, Android's vision was to build operating system for cameras.

Now: Android smartly decided to pivot to produce handsets, and now Android's a smartphone giant, and it's expanded into other areas too, like smart watches and TVs.

Then: They were a company that revolved around selling elementary computer kits.

Now: Apple is a leading hardware and software technology company, selling much more than just computers. According to Forbes, Apple has a $483 billion market cap and is the world's most valuable brand.

Then: Twitter was Odeo, a service that revolved around personal podcasting and sharing audio content.

Now: People use it to share thoughts and updates in 140-character bursts. Twitter had its IPO in November 2013.

Then: It started as Confinity, a cryptography company designed for exchanging money over Palm Pilots. It didn't work well, but they did identify the lucrative market space of enabling people to take credit card payments.

Now: PayPal is the brand-name way to pay for items online. It was acquired by eBay in 2002 for $1.5 billion.

Then: The founders had built a location-based service called Burbn, most comparable to Foursquare. You could check into locations, earn points for hanging out with their friends, and share pictures inside of the app.

Now: Instagram is a hugely popular app for adding artsy filters to your photos and sharing them over Facebook and Twitter. After receiving $57 million in funding, Instagram was acquired by Facebook in 2012.

Then: It was a music recommendation service that only suggested artists you might enjoy.

Now: Pandora is the hugely popular internet radio station tailored to your tastes. It has an $8.5 billion market cap.

Then: Microsoft created BASIC interpreters for the Altair 8800, a microcomputer from the early 70s.

Now: In 1984, Microsoft was the architect behind the Windows software for computer makers, and it's now one of the most popular operating systems in the world. The company has a $343 billion market cap.

Then: It was Facemash, a site comparable to HotOrNot.com, putting two pictures of people next to each other and asking the user to identify which one was "hotter."

Now: It's a social media giant. Since going public in 2012, Facebook has acquired startups like virtual reality company Oculus, messaging service WhatsApp, and Instagram.

Then: Sony made home goods. The first Sony product was a rice cooker, and they soon rolled out a heating blanket.

Now: It's a formidable electronics company with a hand in cameras, video games, computer monitors, and even televisions. Sony has a $20 billion market cap, to boot.

Then: Before there was Pinterest, there was Tote, an ecommerce and social networking website that let people browse different retailers. Tote also sent out alerts when the items users wanted went on sale.

Now: According to Forbes, the people behind Tote realized that its users liked to build and share "collections" of items they liked, so Tote pivoted to Pinterest, the pinboard social network. Pinterest has raised $762.5 million in seven rounds from investors like Andreessen Horowitz, First Round Capital, and Bessemer Venture Partners.

Then: Nintendo got its start at the end of the 19th century in Kyoto, Japan as a playing cards manufacturer. Gizmodo has an excellent story about Nintendo's history.

Now: Nintendo found its niche by making electronic games, which it's still doing today. It's got a market cap of $16 billion.

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