关于网站地图sitemap和ror的说明
1.sitemap.xml
最简单的 Sitemap 形式，就是XML 文件，在其中列出网站中的网址以及关于每个网址的其他元数据（上次更新的时间、更改的频率以及相对于网站上其他网址的重要程度为何等），以便搜索引擎可以更加智能地抓取网站。
这里主要说下ror.xml，这个相比sitemap来说大家比较陌生
2.ror.xml
什么是ROR，引用Alex Jonson说的一句：ROR is Resource of Resource, ROR and XML both are type of site map.也就是说这里的ror不是Ruby on Rails的缩写，Ruby on Rails一个用于编写网络应用程序的框架，它基于计算机软件语言Ruby，给程序开发人员提供强大的框架支持。
而是网站地图的另一种格式而已，是Resources of a Resource的缩写，ror.xml是一种XML格式文件，以分类的形式描述网站的内容、对象、格式，令搜索引擎及其他网上程序更便捷找到和理解该网站信息。
ROR信息可轻易加入网站中、只需要把制作好的ror.xml文件添加到域名根目录下即可。比如，某网站是销售某种产品的，那么ROR可一层层列出产品的名字、描述、价格、形象、功能、合作等等。或者网站的信息也可以被组织起来：站点地图、主题、分类、新闻、档案、blogroll等。再有，ROR可将联系人、文章、新闻信、饲料、图片、声音、链接、评论、隐私政策、版权等更多的对象归档。
以下是原文的一段rorweb官方的说明
ROR (Resources of a Resource) is a rapidly growing independant XML format for describing any object of your content in a generic fashion, so any search engine can better understand that content. RORweb.com is the official ROR website.
ROR promotes the concept of structured feeds (which is related to the concept of structured blogging) enabling search engines to complement text search with structured information to better understand meaning. ROR information is typically stored in a ROR feed called ror.xml placed in your website's main directory. Unlike Google Base, ROR feeds can be easily accessed by all search engines: at http://www.your-website-name.com/ror.xml You can think of your ROR feed as a powerful structured feed for describing all your objects to the search engines: products, services, reviews, discounts, images, events, schedule, podcasts, anything you want.
The current object types and attributes of the ROR format can be found here. We are working with several companies and individuals in defining new object types and attributes for everyone to use. If you want to participate in this effort (i.e. submit a schema, suggest new types and attributes), please contact us at the email address above.
As we expand the ROR format, our goal is to re-use exisisting data structures and formats as much as possible.