TITLE: Distribution of primes?
QUESTION [16 upvotes]: Do primes become more or less frequent as you go further out on the number line?  That is, are there more or fewer primes between $1$ and $1{,}000{,}000$ than between $1{,}000{,}000$ and $2{,}000{,}000$?
A proof or pointer to a proof would be appreciated.

REPLY [5 votes]: The Sieve of Eratosthenes is a very intuitive visual representation of why the frequency of prime numbers goes down as you go further out on the number line.