To put it in simple terms, in a musical context: Allegro means fast; while Moderato means moderately fast. (Actually, the Italian translation of Allegro is actually “happy” and Moderato means “moderate”). But these two terms can be confusing – how do you judge fast? What is moderately fast? And really, the speed really depends on the context of the original score; every piece has different requirements.
You might have even seen some metronomes which indicate Allegro from a certain number to another and other markings such as Andante with a range as well, but this is actually quite ridiculous. Each piece has a certain pulse to it and Allegro can’t be quantified in this way.
The biggest thing to remember is that Fast and Slow are Not Absolutes. The speeds and the markings are simply characters of the piece.
So where exactly to do these terms come from? They are Italian words. This is mostly because Western music has its roots in Western Europe and Italy was a big epicenter for music. Eventually, their terms were adopted by most of the music community.
If you study French or German music, sometimes you will run into a bunch of different terms from their languages. I suggest getting a dictionary, or use online or smartphone resources. Some of the German terms are so long they are almost impossible to pronounce!
Thanks again for watching, Robert Estrin Robert@LivingPianos.com (949) 244-3729