Ramp-PCR is when you make the PCR-program to ramp the temperature down from x to y so you will get a specific annealing. For instance:

  1. 98°C for 2:00 - Denaturing and warm up
  2. 98°C for 0:10 - Denaturing after each cycle
  3. 65°C for 0:05 - Annealing
    • ramp 0.1°C/s until 60°C
  4. 72°C for 2:00 - Elongation
  5. Go to number 2 - repeat 35
  6. 72°C for 5:00 - Final extension
  7. End

A program like that will typically help you if your primers have annealing temperatures in the area between 65°C and 60°C but you don't know the best single step temperature.