These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.
Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.
Why am I hitting a rate limit using Twitter search?
In order to control abuse, Twitter limits how often you can search from a single network address.
If you access Twitter from a corporation, event or conference, you may be sharing the same network address with many people. In some of these cases, you may run into an issue with Twitter search rate limiting.
