The Diagram bellow clearly shows the 7 parts of the E-M spectrum in order of decreasing wavelength, from left to right
An easy way to remember the order is with a mnemonic
For example for the E-M spectrum (RMIVUXG)
you could have:
Reading Music Is Very Unsatisfactory for Xylophones and Glockenspiels
and for the visible portion of the spectrum (ROYGBIV)
Richard Of York Gave Battle In Vain
Or just make up your own...