Laptops work in pretty much the same way as full-sized desktop computers—they just come in a smaller package. Most everything is compressed into the small familiar form factor that you can carry around with you (unlike desktop computers, which typically feature separate display devices and system units).
So when you are learning about your future Mr. (or Ms.) Laptop Computer, you should know that (just like a desktop computer) your laptop will have:
A system unit (which includes the Central Processing Unit, or CPU)
A display device (laptop display devices are generally LCD, or Liquid Crystal Display, screens)
Peripheral devices, probably including a pointing device such as a trackball that takes the place ...