Affected by such variables as pH and anionic or cationic surfactants, it can be measured using a laser Doppler velocimeter, which operates by measuring the electrophoretic mobility of particles, and then using the Smoluchowski or Henry equation to estimate this quantity.  
Derjaguin-Landau-Verwey-Overbeek theory predicts that a larger absolute value for it correlates to greater system stability, since the effects of van der Waals forces are counteracted and particles are less likely to form flocs.  Affected by such variables as pH and anionic or cationic surfactants, it can be measured using a laser Doppler velocimeter, which operates by measuring the electrophoretic mobility of particles, and then using the Smoluchowski or Henry equation to estimate this quantity.  A charged, suspended particle forms a double layer of ions in solvent; this potential forms at surface of hydrodynamic shear between them.  FTP, name this electrical potential, useful as a measure of stability in colloids.
Derjaguin-Landau-Verwey-Overbeek theory predicts that a larger absolute value for it correlates to greater system stability, since the effects of van der Waals forces are counteracted and particles are less likely to form flocs.  
zeta potential (accept colloid before the word "it" in the first sentence)