Under WordPress 1.5, the option to choose between full text or summary feeds is under Options > Reading. How should you choose? If you have a personal blog, go with the full text. Why? Because not everyone likes to have to go to the site and read the whole thing. I’m not alone. If Gary feels that way, how many other people feel the same? The comfort of their news aggregator is good enough. How about a business blog? A summary format be best. I’d hate to see your RSS feed hijacked.
Full text feeds display the whole post within news aggregators, while summary feeds only display part of it. In order for the reader to read the whole post, they need to visit the website. If an excerpt isn’t included, it’ll show the first few lines followed by an ellipse. If you don’t write an excerpt, make sure those first lines grab the reader’s attention.