Manual:nofollow
nofollow は、HTML の <a> 要素の rel 属性に指定できる値であり、一部の検索エンジンに対して、そのハイパーリンクがリンク先の検索エンジンのインデックスにおける順位に影響を与えないよう指示するためのものです。
The configuration setting Manual:$wgNoFollowLinks is used to control whether a wiki's external links should have nofollow or not.
Benefits and costs
恩恵
The main benefit cited for using nofollow is that it deters spam. Mainly this benefit applies to pages where spam could be overlooked and therefore not be reverted.[1] nofollow は主に、nofollow の存在を知っている程度には巧妙だが、nofollow があってもなお投資に見合う効果を得られる可能性があることまでは理解していないスパマーを抑止するためのものです。[2] or aiming for higher returns on investment. nofollow は残念ながら、ウィキが非常に人気であり、スパマーの動機がページ ランクの向上ではなく商品ページへの訪問者を集めることにある場合には、抑止効果がありません。[3] nofollow のもう一つの利点として挙げられているのは、リンク先のサイトにページ ランクを送ることが、それらのサイトや記事の主題にとって有害になり得るという点です。ただし、この「有害」が読者にとって有益なのか有害なのかは明示されていません。たとえば、粗悪な製品を回避する助けになるのであれば、中傷的な情報であっても (むしろ中傷的な情報こそ) 読者にとって有用である可能性があります。
コスト
nofollow を使用すると、ウィキから他サイトへのリンクによって、それらのサイトの検索エンジンにおけるページ ランクが上がるのを防ぐことができます。これは、ウィキの所有者がリンク先のページ ランクを高めたかった場合には都合が悪いことになります。 Turning off nofollow is especially a good idea if you run a private wiki (i.e. one that does not allow editing by anonymous users, and that allows registration by invitation only).[4] In such a case, spamming is not a concern because the spammers lack access to edit. Some public wikis also avoid using nofollow because they want to encourage people to make useful contributions that add external links to their favorite sites.[5] Another cost of nofollow is that there is not yet much capability for using it selectively; it has been argued, "Can you imagine a web that works as good as today's if every link was tagged with nofollow?"[6]
関連項目
- Alternatives to applying the same nofollow/dofollow value to all external links
- The dofollow FAQ
- Manual:スパム対策
脚注
- ↑ Cumbrowski, Carsten (21 January 2007). All Wikipedia Links Are Now NOFOLLOW. This will not eliminate SPAM at Wikipedia, but it will over time certainly reduce it a bit. Especially the spam of invisible pages that have virtually no traffic but at least some PageRank is now virtually a waste of time for any spammer. Spamming of areas with traffic was futile already without the NOFOLLOW attribute in place, since Editors remove the SPAM within hours or even minutes after it happened."
- ↑ Cates, Andrew (22 November 2006). Nofollow. "Some spammers have western type return on effort criteria. Others do not: they live in China with a tiny income and are happy with an incredibly low success rate. If you get a link in Wikipedia it appears in all the mirror sites and many of these (such as answers.com, encyclopedia.worldvillage.com www.algebra.com ) do not use nofollow. The unsophisticated spammer doesn't know about nofollow. The sophisticated spammer knows he gets a return. You may put off a few in the middle and ones who won't accept a miserly pay-back. Also links on Wikipedia generate direct traffic (even us checking if they are genuine). People would spam even for that (some SEO companies even do contracts on a pay per extra visitor basis)."
- ↑ Disaffected Wikipedian (16 February 2008). Post details: MediaWiki software and rel=nofollow.
- ↑ MediaWiki notes, noah.org.
- ↑ Hammock, Rex (22 January 2007). All Wikipedia links are now 'nofollow'. "I’m not so sure this decision by Wikipedia regarding the NOFOLLOW attribute is very beneficial. Why not? It is a feature of most blogging platforms’ comments tool (links appearing in comments are not “indexed” by search engines, in other words) but that does not seem to slow down the attempts by link spammers to clog comments. Also, from my experience of maintaining a rather large and robust wiki, I think one of the reasons individuals participate in helping to create such resources is to pick up some link-love. In other words, I won’t be instituting the nofollow attribute on any mediawiki sites with which I am associated."
- ↑ Mayfield, Ross (11 January 2008). No Free Links and Why nofollow Doesn't Work for Wikis.
外部リンク
- No to Rel="Nofollow", NoNofollow.net
- Evolving “nofollow” – new ways to identify the nature of links, Google Webmaster (2019)
