Explain the advantages and disadvantages of connecting resistors in series in terms of currents and voltages?

For an electrical device, such as a lamp for example, to operate at its rated power, it must be supplied with its rated voltage. If several such devices are to be connected to the same circuit, the only way to achieve this requirement is to connect the devices in parallel (because the same voltage appears across each branch of a parallel circuit). Furthermore, with parallel connections, if one device should fail (or simply get switched off), all the other devices will continue to operate normally. These are the two reasons why most practical circuits are parallel circuits.

Series circuits are less common but can be used for some lighting circuits (e.g. Christmas decorations) in which case the supply voltage is distributed equally across each of the lamps, which then have appropriately-rated voltages. For example, you may have twenty-four, 10-V lamps, connected in series across a 240-V supply.