留萌市

By: Sexy

On: October 15, 2025

Tagged: City, Ground, Island, Mayor, Mountain, Nature, Ocean

With: 0 Comments

留萌市（るもいし）は、北海道北部の市。留萌振興局の振興局所在地。留萌地方の中心の都市である。主な産業は貿易などの商業、土木業、水産加工業である。留萌港では現今においてもニシンが水揚げされ、その魚卵であるカズノコの国内最大の加工地である。

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Spider

Web crawler, sometimes called a spider or spiderbot and often shortened to crawler, is an Internet bot that systematically browses the World Wide Web and that is typically operated by search engines for the purpose of Web indexing (web spidering).

Web search engines and some other websites use Web crawling or spidering software to update their web content or indices of other sites' web content. Web crawlers copy pages for processing by a search engine, which indexes the downloaded pages so that users can search more efficiently.

Crawlers consume resources on visited systems and often visit sites unprompted. Issues of schedule, load, and "politeness" come into play when large collections of pages are accessed. Mechanisms exist for public sites not wishing to be crawled to make this known to the crawling agent. For example, including a robots.txt file can request bots to index only parts of a website, or nothing at all.

The number of Internet pages is extremely large; even the largest crawlers fall short of making a complete index. For this reason, search engines struggled to give relevant search results in the early years of the World Wide Web, before 2000. Today, relevant results are given almost instantly.

Crawlers can validate hyperlinks and HTML code. They can also be used for web scraping and data-driven programming.