generate questions: Snapshots usually become available more than six months after they are archived or, in some cases, even later; it can take twenty-four months or longer.  The frequency of snapshots is variable, so not all tracked web site updates are recorded. Sometimes there are intervals of several weeks or years between snapshots.
What are the saved versions of a site called? {sep_token} What is the minimum amount of time that elapses before most snapshots are released for viewing? {sep_token} What term characterizes the rate at which snapshots are made of websites?