According to the Wikipedia,
""Information of an entity is that which resolves the uncertainty of its properties""
Information contained in a physical system = the number of yes/no questions you need to get answered to fully specify the system.
But there are more then one perspective about information notion, p.e.
Shannon information theory, usually called just ‘information’ theory and Kolmogorov complexity theory the ‘algorithmic information’ theory,
Both theories aim at providing a means for measuring‘information’.
Both are measures of the smallest number of bits that can be used to regenerate a string perfectly.
With the signifiant difference that the Kolmogorov complexity approach is in an algorithm context
Shannon entropy can be considered in approximation as the estimation of the Kolmogorov complexity.
The concept of Entropy is the common thread that connects physical world (mass, energy) the world of uncertainity of events or existent (Information).
The informationn concept seems to be quite complex indeed already a question can emerges about the true ""nature"" of information,... and the link made by Entropy between Energy, Mass and Information
see this post :
but come back to Shannon Entropy and its measure:
Shannon Entropy of well-encrypted stream is equal to Shannon Entropy of random noise.
...information can not be define only based on data...? but we can ask the question if in the Kolmogorov complexity context, the algorithm used can be considered as a ""knowledge"" about ""reciever""..?
Are knowledge about data and receiver are needed,....?
Change in the receiver's state would be the only way to measure how much information is contained in the message.. ? ....so subjective
how can go deeper in the problematic about the true ""nature"" of information ..?