用于查找大量的Web页面。它从一个简单的Web页面上开始执行，然后通过其超链接在访问其他页面，如此反复理论上可以扫描互联网上的所有页面。-Used to find a large number of Web pages. It is from a simple Web page started, and then, through its hyperlinks to other pages in the visit, and so again in theory can scan all the pages on the Internet.