When Rousseau wrote his social theory, concepts of liberty and freedom were not new ideas. Hints of social contract reasoning are found in earlier works, most notably in Book 2 of Plato's dialog The Republic, as well as, in Socrates.
The total spending per iTunes account is $43 per year across all media, says Dediu. At 575 million iTunes accounts, that works out to $24.7 billion of consumer spending at iTunes per year. The average iTunes account's annual spending on software has followed music's trend, falling to $9 from $42 in 2008. However, average annual spending on apps has gone in the opposite direction, rising to $16 this year from $7 in 2008.
iTunes and App Store gift cards are basically the same thing, both are redeemed onto your iTunes account and can be used to buy from the iTunes store, app store, Mac app store on Mac computers and the iBookstore-the cards that you shouldn't buy are Apple Store gift cards, they cannot be used with an iTunes account.