ASP.NET 4.0's Page class has two new properties that allow you to set the keyword and description metatags that are generated: MetaKeywords and MetaDescription. It is worth noting that most search engines (or certainly the big one beginning with G) probably ignore metatags (because of previous abuse), and if you have already specified metatags on your page, then MetaKeywords and MetaDescription will act as properties, so make sure you append rather than overwrite when using them.
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