I'm not clear why the "string tension" of string theory is so called. Perhaps folk here can help with this elementary point. It is not really the same as the "string tension" of a musical instrument, say a guitar or a piano, although such a musical-instrument analogy is often used. In stringed instruments tension is but one kind of internal stress in a composite object made of strings and a body. The internal stress in the string part of the instrument is tensile and is compensated for by compressive stresses in its body part (exactly if the instrument is free-standing). These internal stresses arise from distortions of the stuff of which the instrument is made, and are electromagnetic in nature. But the strings of string theory are not made of stuff that is distorted, nor are they parts of some composite object. So in its details the musical-instrument analogy breaks down. Neither is "string tension" quite the same as a one-dimensional version of the "tension" in a liquid surface, even though surface tension has the same units as surface energy, just as "string tension" has the same units as energy per unit length. But surface tension arises because surface atoms are less strongly bound than those inside the liquid, whereas strings are thought to be one-dimensional and such distinctions don't arise. Nor are strings known to be made of smaller entities, as liquids are. So this isn't a close analogy, either, and "tension" is perhaps an inappropriate word to use. "String tension" seems to me to be just the energy (or mass) per unit length of a one-dimensional entity; an energy which is both sufficiently large to account for quantum gravity and to make the entity shrink to Planck-scale dimensions. Is this all "string tension" is? Finally, I don't understand why strings eventually stop shrinking. What's to stop them making like Oozlum birds?