The transposition technique uses some form of permutations over the plain text to encrypt the data and convert plain text into ciphertext. This technique is known as transposition cipher.

An example of such cipher is the Rail fence cipher

in which, the plain text was written down as a sequence of diagonals and read them in row by row, you will get a jumbled up message.
 for example, let's take a message " Today maths teacher is absent "

 Its sequence of diagonals will be
 T d y a h t a h r s b e t 
 o a m t s e c e i a s n

cipher text will be " Tdyahtahrsbedoamtseceiasn"

There are more complex versions of writing such ways like writing the message in a rectangle in row by row and now read the message off in column by column. but before reading off in column by column we permutate the order of column numbers. and then the order of columns becomes the key.

 For example "Mantis shrimp has the fastest punch"
 key: 6 2 7 3 4 1 5
 plaintext:  M   a  n   t    i   s   s
                 h   r   i   m  p   h  a
                 s   t   h  e    f   a   s 
                 t   e   s   t   p   u   n 
                 c   h  a   b   c   d   e

in the above case, 6273415 is the key for the encryption. i.e., write down the column labeled 1. in this case it was column 6 and write down column 2, which is in column 2 itself. and so on

 but the above cipher has the same frequency of letters as in plain text. it is essentially the same data but jumbled. which leaves the information about the frequency of letters.

To address this issue, the transposition cipher can be made more secure by performing the transposition more than once. the result is more complex data to deal with and hard to reconstruct the original message.