In recent years, fractional calculus has been a subject of numerous investigations by scientists from mathematics, physics, and engineering communities. The widespread interest in this area of research arises mainly from its applications to many models in the fields of fluid mechanics, viscoelasticity, electromagnetic, acoustics, chemistry, biology, physics, neuron modeling, and material sciences. Therefore, the literature reveals a considerable amount of work on the field of fractional calculus and its applications. Besides, the discrete fractional calculus has attracted many researchers in different fields of science and engineering and has been theoretically developed fast in the last two decades.

In this special issue, we will focus on the recent theoretical andnumerical studiesondifference and fractional differential equations.

Potential topics include but are not limited to the following:

• Fractional differential equations
• Fractional difference and q-difference equations
• Fractional difference and q-fractional difference variational calculus
• Oscillation criteria for fractional and fractional difference dynamical systems
• Fractional integrodifferential equations
• System of integrodifferential equations
• System of fractional integrodifferential equations