Newsletters are information e-mails which are sent to subscribers. They can include advertisements in various forms (Text, Display Advertising, etc...).
Careful selection of the topics addressed permits targeting based on personal interests.
"RSS feeds" are generated broadcast information feeds to which the user subscribes. Each time new content is placed online, the web-surfer sees it appear in his aggregator. He can consult the summary, click on the update and download the entirety of the content, or visit the issuing site.
Advertising messages can be inserted into these information feeds, thereby allowing the advertiser to publish information on its products, promotions, etc.
This channel fits into the Web 2.0 evolution in that it allows web-surfers to choose their information sources and combine them without having to keep connecting to the different websites. He or she is free to subscribe or unsubscribe at any moment.