There are two basic components that make up a steel string: a core and a wrap. When you look at the two smallest strings on an acoustic guitar, you are basically looking at an unwound core string. Wild, huh? Those naked little B and high E strings look just like their four bigger brothers minus that shiny bronze wrapping. Now, when we talk about tension on a guitar we are pretty much talking about lateral tension -- that is, the force that the individual strings exert laterally across the neck and soundboard of the instrument. [Note: this differs from instruments with floating bridges (mandolins, banjos, arch top guitars, etc.) where downward, or vertical tension becomes more important -- for more on this check out Siminoff Strings]. Now given the two basic components of a steel string, what would you say determines lateral tension? Well, if you guessed the wrapping, I'm happy to say you are absolutely wrong...It's the core, of course! A string's core determines its lateral tension -- remember that!