Earphones are simply a set of small loudspeakers worn around or on the head by a user. They are electro-acoustic transducers, that convert an electric signal into a corresponding sound. They are usually worn in one ear and play back the sound through the other. Most earphones have a microphone built into them, so that they can pick up an audio signal and convert it into sound. Many earphones will also have a volume control to adjust the volume of the audio being played back.
There are many types of earphones, with some differing from others. One type of earphone, called ear buds, sit right behind the ear canal in order to capture the sound waves. Another type of earphone, called earbuds (or in some cases, surround earbuds) are put right in front of the ear canal to capture the sound waves, again in front of the ear canal for best effects. The third type of earphone is the earphone over the head, often called Bluetooth earbuds or simply Bluetooth earbuds. These earbuds are usually placed in the ear canal and often provide a better sound quality than other kinds of earbuds.
The two main types of headphones are over the heads, and in the ear. Over the heads, such as Bluetooth earbuds, generally work through the use of wires to get the audio from the source of the headphones to the headphones. Under the heads, such as with Bluetooth earbuds, there are no wires at all and the headphones work this way because of the wireless technology used. Wireless headphones have become a popular option due to the fact that they are very easy to use and can work with any kind of phone/computer/listening device. Headphones have come a long way from their humble beginnings and have evolved into high-tech gadgets.