When you rearrange your text in a "wave" sort of pattern (down, down, up, up, down, down, etc.), it is called a railfence. Take the text "WAFFLES FOR BREAKFAST" and arrange them in waves like the diagram below. I substituted * for spaces just to illustrate that the spaces are not removed.

W   L   F   B   K   T
 A F E * O * R A F S
  F   S   R   E   A

You leave the spaces in. Next, you squish together the lines, remembering to keep the spaces in. I did not replace spaces with stars since the spaces are clearly shown in the middle line.

WLFBKT
AFE O RAFS
FSREA

Then you just combine the lines and get WLFBKTAFE O RAFSFSREA. Or you can use this JavaScript-based tool and speed things up quite a bit. There is another site with more of a description and another encoder.

Encrypt Decrypt

Rails: – The number of rows, which determines the height of the waves.

Offset: – Instead of starting on the top rail and working down, you can start on any rail and move up or down depending on where you place the offset. Should be less than (rail * 2 - 1).

Your message:

Show the rails

This is your encoded or decoded text. It may be hard to see spaces at the beginning, end, or two in a row. Be careful when copying encrypted text and make sure that it will decrypt to the message properly.