Piano tablature (or "piano tab" for short) is an abbreviated method of music notation. While used for modern pop music, the idea is nothing new: interestingly, tablature for keyboard instruments has been around since the mid-fifteenth century!
Tablature derives from the Latin word meaning to tabulate or put into a table. Tablature was originally designed for fretted string instruments (such as the lute or guitar), and it represents fingering rather than the actual notes. In contrast to tablature for other instruments, however, piano tablature represents the piano's keys rather than the fingers.
The primary difference between piano tablature and standard notation is that tablature tells which keys to press, while standard notation tells which notes to play. (See How to Read Piano Tabs for details.) As key-notes readers know, however, the keys are not the notes! This reveals an immediate disadvantage to tablature notation, since critical harmonic information is missing altogether.
There is a trade-off between simplicity and detail. In the case of music notation, this means that tablature is often inaccurate or at least very limited in its ability to represent music.
Tablature can indeed be an adequate means of transmitting music in writing, but it only works for basic music. Tuplets, counterpoint, voice crossing, polyrhythms, keys... none of these musical essentials can be notated effectively using piano tablature. Ironically, attempting to represent more complex piano music in simplified tablature form can actually become much more complex than traditional notation!
Interestingly, there are no accidentals in piano tablature notation. While this may simplify reading, it ultimately works to the detriment of musicians. For example, F is an entirely different note from E-sharp, even though both notes are played by the same key on the piano. The notes can have very different functions in actual music, and psychoacoustically they can even seem to sound different, depending on context... even though their pitch is identical! A convincing demonstration of this psychoacoustic phenomenon can be heard on the Piano Theory page.
Since there is an inherent dialectic between music as heard and written music, composers who would restrict their knowledge of writing music to piano tablature are likely to limit their creativity inadvertently.
The only real advantage to piano tablature is that it is easier to read for beginning music students. Even this advantage turns out to be a handicap in disguise, since students will ultimately need to learn standard musical notation if they are to progress in their studies.
The good news, though, is that piano tablature really is easy to learn, assuming the music represented remains simple. This means that it shouldn't be too difficult to learn a piece from tabs if it's the only sheet music available.
Next lesson: How to Read Piano Tabs