Will keeping my laptop plugged in hurt battery?

HEY EVERYONE!

I purchased a Dell Inspiron 15z with Touchscreen.

because I had too ,many Problems with the battery of my old Laptop I´m willing now to do the best that i can in order to Keep the battery´s life good.

because it  a built-in-battery-Laptop I cant remove the battery when im home. so I Need to know

If I should Keep my Laptop plugged in to the AC Adapter also after its fully charged? or should I only Charge it to 100% then unplug it til it reachs the 5 % for example and so...

thanks alot !!