What are the different forms of head in fluid flow?

Head represents energy per unit weight of fluid and has three main forms: (1) Pressure head (P/ρg) - energy due to fluid pressure, measured in meters of fluid column. (2) Velocity head (V²/2g) - kinetic energy of flowing fluid. (3) Elevation head (z) - potential energy due to height above a reference datum. The total head is the sum of all three: H_total = P/ρg + V²/2g + z. In pump systems, we also consider friction head (energy lost to friction) and pump head (energy added by pump).