I've been playing violin/viola for over 20 years now and I still find it hard to describe harmonics, lol. There's like a whole physics lecture behind them and most of it goes over my head Basically, there are two kinds of string harmonics: natural and artificial. In short, natural harmonics occur when the player lightly touches a point on the string to produce the harmonic tone. These are a little confusing to notate since what one might see on the page isn't necessarily the pitch heard. I In the example above, it's basically telling the player to lightly touch the note where the player would normally play the E on the open G string. This will produce the B harmonic (as notated in the parenthesis). Some composers might just notate the diamond note on the E, and not have the G...players will know what to do. . Artificial harmonics are a little easier to notate. In the example above, you're telling the player to press the string (in this case the G string...the IV means G string...but the B notated is only possible on the G string so it's redundant) with the 1st finger (the index finger), and then lightly touch with their pinky finger a fourth above (if the player presses hard with their pinky finger, the note produced will be an E). The resulting pitch will be a B, but a harmonic that sounds 2 octaves higher than notated. These perfect 4th harmonics are pretty much standard in orchestral repertoire and will always produce the lower regular note 2 octaves higher than notated. Obviously, you can't do these harmonics on open strings, there always has to be a stopped note. Both examples above will produce the same B harmonic. The natural harmonic might be easier for players to play/find. Hopefully that made sense!