Every electrical and electronic component, every connecting line and every connecting wire forms a small parasitic capacitance to other live lines. Such a parasitic capacitance is a stray capacitance.
Stray capacitances are unwanted capacitances that affect signal transmissiondepending on their magnitude and frequency. The influence of stray capacitances increases with increasing frequency. The size of stray capacitances depends on the distance between two live lines, surfaces or components. The closer two components are to each other, the greater the stray capacitance between them. In the case of lines, the line diameter plays an important role, as does the length that two lines lie next to each other.
Stray capacitances also occur in passive components such as coils and capacitors, especially if they have conductive connection surfaces as SMD components or if their outer sheathing is not potential-free.