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/20110106213231/http://www.searchengineoptimising.com/glossary/glossary-of-computer-and-internet-terms/null
Null is used when something has no value. It is not 0 as 0 has a value. In boolean tests 0 and null both have a false value and as a result boolean texts are favoured by programmers as they will show if a variable has a value or not.