Capacitance means 'the ability to store the charge' and stray means 'not in the right place'. Therefore we can say that if capacitance is established anywhere (may be in a device or between devices) without ordinary capacitor, then it is called as stray or parasitic capacitance.
Capacitance doesn't exist only within capacitors. Actually any two surfaces/bodies/regions at different electric potential are separated by few distance or dielectric somehow provides some capacitance.
Stray capacitance always exists among leads of the devices, between two conductor wires, between p and n regions of diodes etc. This is unwanted but unavoidable capacitance and referred as different names in different cases such as Parasitic Capacitance.
Designers of circuits try to minimize stray capacitance as much as possible among several devices. They do this by keeping the leads of electronic components very short and grouping components in such a way to eliminate capacitive coupling.
At low frequencies, parasitic or stray capacitance can usually be ignored. However, in high-frequency circuits/components, it can be a major problem. The capacitive reactance (Xc) is inversely proportional to the product of the frequency and capacitance, [Xc = 1 / (2*pi*f*c)]. As the frequency increases, the capacitive reactance decreases, resulting in more current flowing through the capacitor. That is why electronic components are modified for high frequencies (microwaves).
In conclusion, understanding the concept of capacitance and stray capacitance is crucial in the design and development of electronic devices and circuits. It is essential to minimize stray capacitance and to consider the effects of capacitance at high frequencies to ensure optimal performance and functionality.
