The advantages of connecting electrical devices in parallel are the following:
(i) In parallel circuits, if one electrical appliance stops working due to some defect, than all other appliances keep working normally. On the other hand, in series circuit, if one electrical appliance stops working due to some defect, then all other appliances also stop working (because the whole circuit is broken).
(ii) In parallel circuits, each electrical appliance has its own switch due to which it can be turned on or turned off independently, without affecting other appliances. In series circuit, all the electrical appliances have only one switch due to which they cannot be turned on or turned off independently.
(iii) In parallel circuits, each electrical appliance gets the same voltage as that of the battery due to which all the appliances work properly. In series circuit, the appliances do not get the same voltage as that of the battery because the voltage is shared by all the appliances.
(iv) In the parallel connection of electrical appliances, the overall resistance of the circuit is reduced due to which the current from the battery is high and hence each electrical appliance can draw the required amount of current. In the series connection of electrical appliances, the overall resistance of the circuit increases too much due to which the curren from the battery is low and hence all the electrical appliances cannot draw sufficient current for their proper working.