What are the disadvantages in using a series circuit?

Series:

It is impossible to control the bulbs individually. This is one reason that series circuits are not practical for use in home lighting: It is not possible to control the lights in different rooms throughout the house on the same circuit. For example, if someone wanted to read the newspaper or watch television, he would have to turn on a switch that would put on every light and electrical appliance in the whole house.

Also, in a series circuit, the more output devices you add the slower the current becomes. If these output devices were, for example, bulbs, this would mean that the brightness of the bulbs would be dimmed. Another disadvantage of a series circuit is that if a bulb were broken or the pathway broken in any way, the other bulbs would go out too.

Advantages are that you can add more power sources, like batteries, and increase the force of the output which grants you more power. In Parallel, however, the power stays at the same voltage of the original power source. For example, if you were running a circuit on a 5-volt battery and it kept the bulb going for two hours and then added another 5-volt battery, it would keep the bulbs going for four hours instead, but it would only give out 5-volts instead of increasing it to ten.

Parallel:

Advantages would be that, if it were light bulbs that were the output devices linked in parallel, if one bulb broke the others would continue going. Also, the brightness of the bulbs would be greater than the brightness of bulbs in series.

Disadvantages are that there could be a risk of fire in some cases. Another would be that, if you have multiple power sources, the power stays at the same voltage as that of the single power source. In parallel, increasing the number of output devices does not increase the resistance like it does in series.