In the last 20 years, the topic of episodic accretion has gained significant interest in the star formation community. it is now viewed as a common, though still poorly understood phenomenon in low mass star formation. The FU Orionis objects are long studied examples of this phenomenon. FUors are believed to undergo accretion outbursts during which
the accretion rate rapidly increases from typically 10^−7 to a few 10^−4 M⊙ yr^−1 , and remains elevated over several decades or more. EXors, a loosely defined class of pre-main sequence stars, exhibit shorter and repetitive outbursts, associated with lower accretion rates. In this talk, I will give a brief introduction about the nature of episodic accretion in these two sub groups and the current theoretical models which has been developed to explain this phenomena .