To send information in the form of a message you need to choose an agreed code, i.e. a set of symbols that both sender and receiver understand. This
gives us a language to convey or store information. Binary and analog signals are just two examples of types of codes. English, French, Braille,
Hieroglyphics and Klingon are all examples of codes.
We can convert information from one code into another without losing any of the details - provided we do it correctly. As a result we can always turn information into a convenient form, be it Japanese, marine flags or binary bits.
It is the agreed regularity of a code or language that makes it possible to use it to communicate information. Hence, to understand a message the receiver has to know the correct code. For most purposes it makes sense to agree a coding scheme (language) which is as efficient and clear as possible. However, in some circumstances it is important to be able to ‘hide’ information from unauthorised evesdroppers. In these circumstances we want to keep the code ‘secret’. This leads to the important topic of secret codes and cyphers.
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