NEW YORK ( TheStreet) -- Popular searches on the Internet Thursday include "iPhone birthday," one day after Apple's ( AAPL) iPhone turned four years old.

The original iPhone first went on sale on June 29, 2007, for $500, introducing the world to a large touchscreen smartphone. Today's current version is the iPhone 4, with the iPhone 4S and iPhone 5 rumored to be on the way. The thickness of the iPhone 4 has been reduced from the original, with an updated camera and faster processor.

Another popular topic on the Web Thursday is "QR code" -- otherwise known as Quick Response code.

These codes are matrix barcodes that are readable by camera phones and include encoded information such as text, URLs or other data. The use of QR codes is growing rapidly, with small businesses and major brands using them as marketing tools. Even companies like Microsoft ( MSFT) are attempting to get a piece of the action, launching its Tag codes as an alternative to QR codes.

"Google Wave" is another hot trend, after Google's ( GOOG) introduction of the +1 button.

Google's +1 button, which users can click to recommend content they like to their friends, is prompting speculation around the Internet about whether it will suffer the same fate as Google's failed Wave. Google Wave attempted to help users communicate and collaborate on the Web, but is no longer being developed as a standalone product.

The chatter on Main Street (a.k.a. Google, Yahoo! and other search sites) is always of interest to investors on Wall Street. Thus, each day, TheStreet compiles the stories that are trending on the Web, and highlights the news that could make stocks move.

-- Written by Brittany Umar.
Brittany joined TV in November 2006 after completing a degree in Journalism and Media Studies at Rutgers College. Previously, Brittany interned at the local ABC affiliate in New York City WABC-TV 7 where she helped research and produce On Your Side, a popular consumer advocacy segment.