The Internet Archive discovers and captures web pages through many different web crawls.
At any given time several distinct crawls are running, some for months, and some every day or longer.
View the web archive through the Wayback Machine.
Web wide crawl with initial seedlist and crawler configuration from October 2010
TIMESTAMPS
The Wayback Machine - https://web.archive.org/web/20110106202005/http://www.searchengineoptimising.com/glossary/glossary-of-computer-and-internet-terms/cpa
CPA or Cost Per Action is the term used to describe the fee that is charged each time a desired action is completed by a user, this can take the form of reading a number of pages or downloading particular software.