As a developer, I can assure you of the importance of rich text formatting in user requests—especially in issue descriptions—for good text comprehension. It is especially important if the one who is going to comprehend an issue (for example) is constantly dealing with a lot of such issues. In practice, users unfortunately neglect rich formatting often, what results in bad readability and sometimes distorted message layouts (when some characters are treated as formatting markers). Therefore, I believe that familiarity with Redmine text formatting is essential for using this application. Luckily, the syntax of the formatting language is not too complicated, as it's based on a plain-text markup language.
Redmine currently comes with native support for two markup languages—Textile and Markdown. However, we will focus mainly on the former (while mentioning the latter whenever possible). There are two reasons for this. Firstly, most Redmine installations (still) use Textile...