If your house was wired in series, all it would take is one light bulb to blow ans the entire house would be without electricity. Simply, everything in the house would be in one continuous loop. Any break in the loop would cause the entire loop to close down and until you find the break, you are without electricity. As an example, a Christmas Tree woth a strand of 10,000 lights in series, if one bulb burns out all the lights go out and you have to test every one of the 10,00 bulbs until you find the bad one. As "Dirty Harry" said, "Do you feel lucky?"
Because the parallel circuit has two or more paths and the series circuit has only one path