A metronome works by playing a sound (usually a click or a beep) at a certain number of beats per minute. If you can imagine a second hand ticking, that is 60 beats per minute (1 second = 1 beat). If there were 3 beats per second (3 beats * 60 seconds), then the tempo would be 180 bpm. Time and tempo are the same for all instrumentalists (it is how they can play together!), so you will never need a specialized metronome for your instrument.
Musicians use metronomes to find and feel the tempo of a piece of music. Imagine that you are looking at a piece that you have never heard before. You can hear the melody because you can see the notes on the staff, but how do you know how fast (or slow) it is supposed to go? This is where a tempo marking and a metronome come in handy.
A metronome will also help establish more disciplined practice. Imagine you have a really hard section in a song that you want to play, you can (and should) slow the tempo down to really concentrate on making sure that each note is perfect. Once you have mastered the articulation, the tone, the intonation, the dynamic, and the rhythm, then you can begin to increase the speed gradually.
Finally, a metronome is useful for practicing rhythms. Music is basically made up of two elements: pitch and rhythm. Musicians practice by breaking music into smaller pieces to isolate problems. If you are struggling with rhythm then counting or clapping rhythms with the beat can help to fix the moment where your error occurs.
A general rule is to practice small sections of music at a time. Yes, it is important to run through the entire piece to make sure you have the endurance, but when you are fixing problems, you should only practice a few measures at a time. Here is a sample process for fixing any problem:
A rhythm lets musicians know when a note should be played and how long a note should be played for. Here are some of the most common rhythms musicians see and how many beats they get.
This will be true for all simple meters (where notes are divided into two). They will be divided slightly differently in compound meter (where notes are divided into three).
Tempo markings let musicians know the speed or tempo of a song. They can be written in two ways: a word or a number. The numerical representation is more precise and is written in beats per minute or BPM. Think about a second hand ticking on a clock. There are 60 seconds in a minute, so a clock ticks at 60 bpm. If you were to make the clock tick twice as fast then it would be going at 120 bpm.
Composers will sometimes instruct tempo with a word or phrase like �Allegro.� These are typically in Italian, French, German, or English if it is a modern composition. Here is a list of common tempo markings and their beats per minute.
A time signature lets a musician know how many beats are in a measure and which note will receive the beat.
When you look at a time signature, you will see two numbers. The top number lets you know how many beats are in a measure. The bottom number lets you know which note will get the beat. One of the most common time signatures is 4/4. The top number is 4, so we know that there are going to be 4 beats per measure. The bottom number is 4, so we know that the quarter note will get the beat.
Take a look at the list below. It will show you the note value that corresponds with the bottom number in a time signature.
Using the above, you would know that if the time signature was 3/4, then there are 3 beats per measure and the quarter note would get the beat. If you are practicing with a metronome, it can be very useful to switch the accent of the note to be the first note of each measure.
Time signatures don't tell you anything about tempo, they just tell you where the beat will be placed.