Shift register and Dot matrix led

With any digital circuit, noise is generated when the internal gates and other circuits switch from one state to an other, the faster the switching, usually means more noise. Power traces on a board are not perfect (0 Ohms) so therefore there is always a voltage drop along the trace, also there is inductance and capacitance to other nearby traces. decoupling capacitors are designed into the circuits to help manage this and provide easy paths of any noise generated to get back to ground rather than nearby signal traces

Noise is the "Interference" on the power and possibly other lines that if left un-checked can end up interfering with the normal operation of the circuit

larger electrolytic capacitors will provide low frequency decoupling and to a certain extent an additional source for short period increases of current requirements

the smaller ceramic caps (Or other material) are used for high frequency decoupling  and will effectively provide a short to ground of this noise.

Why both, well Electrolytic are great for lower frequencies but internal construction tends to add inductance, series resistance and other factors that cause them to be less affective at the higher frequency ranges (capacitors are not perfect even though we would like them to be) so we add small value ceramic caps to provide the high frequency decoupling that the electrolysis can not handle

With any digital circuit, noise is generated when the internal gates and other circuits switch from one state to an other, the faster the switching, usually means more noise. Power traces on a board are not perfect (0 Ohms) so therefore there is always a voltage drop along the trace, also there is inductance and capacitance to other nearby traces. decoupling capacitors are designed into the circuits to help manage this and provide easy paths of any noise generated to get back to ground rather than nearby signal traces

Noise is the "Interference" on the power and possibly other lines that if left un-checked can end up interfering with the normal operation of the circuit

larger electrolytic capacitors will provide low frequency decoupling and to a certain extent an additional source for short period increases of current requirements

the smaller ceramic caps (Or other material) are used for high frequency decoupling  and will effectively provide a short to ground of this noise.

Why both, well Electrolytic are great for lower frequencies but internal construction tends to add inductance, series resistance and other factors that cause them to be less affective at the higher frequency ranges (capacitors are not perfect even though we would like them to be) so we add small value ceramic caps to provide the high frequency decoupling that the electrolysis can not handle