A gel is a solid jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid. It is the crosslinking within the fluid that gives a gel its structure (hardness) and contributes to the adhesive stick (tack). In this way gels are a dispersion of molecules of a liquid within a solid in which the solid is the continuous phase and the liquid is the discontinuous phase. The word gel was coined by 19th-century Scottish chemist Thomas Graham by clipping from gelatin.

PCR, polymerase chain reaction

TAQ or Pfu or Pfx or other enzymes are used for polycmerase chain reaction and have different specificity. The mores specific the lower the yield.

Thermocyclers can be callibrated for identical ramping curves to obtain a more accurate PCR.