Auto URL-detection is available for http hyperlinks. This feature is not enabled by default. You can turn on auto URL-detection by using the options screen.
When this feature is active, after typing a URL into the article which starts with 'http', this URL will be automatically converted to a hyperlink of underlined type.
Note After typing a 'http' URL into a plain-text article, not only the URL will be reformatted, but the entire article will be converted to Rich Text format. If you want to limit your database to plain-text articles (e.g. to reduce database size) you should not have this option activated.