I have come through many places stating capacitors as coupling and decoupling capacitors, but I can't understand what is meant by coupling and de-coupling capacitors?
Can anyone explain me what they are and how do they differ from normal capacitors??
They are no different from normal capacitors. The Decoupling and Coupling refers to how the capacitors are used, not what they are made of or anything.
A decoupling capacitor is used as a mini battery or energy reserve. By placing it near an IC's power pins, it helps keep the power line steady, avoiding the minor fluctuations and ripple that exist in power circuits:
Decoupling capacitors are typically in parallel with an IC or circuit.
Coupling capacitors on the other hand:
Coupling capacitors are typically in series with the signal.
Both types are typically common non-polarity-specific ceramic capacitors.