Voltage across parallel resistances

Imagine now a set of ornamental light bulbs connected in parallel (Fig. 1). This is the method used for outdoor holiday lighting, or for bright indoor lighting. It’s much easier to fix a parallel-wired string of holiday lights if one bulb should burn out than it is to fix a series-wired string. And the failure of one bulb does not cause catastrophic system failure. In fact, it might be awhile before you notice that the bulb is dark, because all the other ones will stay lit, and their brightness will not change.

Fig. 1 Light bulbs in parallel.

In a parallel circuit, the voltage across each component is always the same and it is always equal to the supply or battery voltage. The current drawn by each component depends only on the resistance of that particular device. In this sense, the components in a parallel-wired circuit work independently, as opposed to the series-wired circuit in which they all interact.
If any one branch of a parallel circuit is taken away, the conditions in the other branches will remain the same. If new branches are added, assuming the power supply can handle the load, conditions in previously existing branches will not be affected.