"The term "earphones" covers a range of products that vary widely in appearance and in technology, so we'll narrow the field down to models that can be used on the go. Even so, there's still a wide range of diversity in that category. There are many different ways of "injecting" sound into a pair of ears; each has its advantages and disadvantages, and is better suited to a particular type of user's tastes and listening habits. Remove the earphones slightly from your ears and you'll notice that the sound is totally altered. The bass frequencies disappear - and even the midrange - and all you hear is the high notes. This phenomenon is well known, and very unpleasant when the person next to you is listening to music with earphones."
Wow, this is one hell of a review on headphones. The author starts with a guide on what aspects of audio are best for headphones and then goes on to describe the best qualities for headphones. He then not only gives a mini-review on each headphone but also compares it against the previously set criteria. Honestly, I feel quite educated now. I definitely recommend this article.