Wireless has been around many years in the form of IR and RF, but it has always had limited usability. Various companies realized the need for a new wireless technology that was both cheap to make and didn't require a lot of power. So came Bluetooth. Bluetooth was developed to allow short-range wireless communications to be used in many of your handheld devices. This technology would work across vendors and platforms, worldwide even! The developers imagined Bluetooth in our phones, palm devices, and even our PCs. Well they have done it. Bluetooth is supported by 2000 OEMs worldwide and there is over 1000 Bluetooth devices on store shelves to date, I even have two at home now!.
You may ask what does Bluetooth do? It allows the all Bluetooth devices to connect together and share information. The Bluetooth specification provides for voice and data transmission, normally 30" meters, but can be extended to 400". Envision mobile phones talking to your PC, your Palm-Pilot accessing the Internet through the phone in your pocket. That's what Bluetooth does, that's what the developers wanted.
Why wouldn't every company try to make there own version of wireless? The one word answer is: compatibility. Bluetooth SIG started out as a volunteer organization. People with in the communications/technology industry volunteered their time to create the earliest specifications now know as Bluetooth. The Bluetooth SIG now as a few permanent staff and has various volunteer staff that work in the form of "work groups". These volunteers work for the companies that design Bluetooth devices, IBM and Microsoft to name a few. They want this to be come the industry wide specification for short-range wireless technology. .
In a nutshell Bluetooth is a lot of things: cheap to produce, energy efficient, secure, and resists interference from other RF noise. Bluetooth runs on the 2.4-gigahertz range, which is an unlicensed band range.