Hi,
Ceramic, due to its compact size and low cost. Low value Ceramic is used for high frequency bypassing whereas High value Aluminium or Tantalum Electrolytic Capacitrs are used for Low frequency bypassing.
Regards, Laktronics
Ceramic capacitors are constructed with materials such as titanium acid barium used as the dielectric. Internally, these capacitors are not constructed as a coil, so they can be used in high frequency applications. Typically, they are used in circuits which bypass high frequency signals to ground.
These capacitors have the shape of a disk (mostly). Their capacitance is comparatively small.