For example, starting lines of text with asterisks could create a bulleted list. The style and syntax of wikitexts can vary greatly among wiki implementations, some of which also allow HTML tags. Layout consistency Wikis have favored plain-text editing, with fewer and simpler conventions than HTML for indicating style and structure. Although limiting access to HTML and Cascading Style Sheets (CSS) of wikis limits user ability to alter the structure and formatting of wiki content, there are some benefits. Limited access to CSS promotes consistency in the look and feel, and having JavaScript disabled prevents a user from implementing code that may limit other users' access. Basic syntax Visual editing Wikis can also make WYSIWYG editing available to users, usually through a JavaScript control that translates graphically entered formatting instructions into the corresponding HTML tags or wikitext. In those implementations, the markup of a newly edited, marked-up version of the page is generated and submitted to the server transparently, shielding the user from this technical detail. An example of this is the VisualEditor on Wikipedia. WYSIWYG controls do not, however, always provide all the features available in wikitext, and some users prefer not to use a WYSIWYG editor. Hence, many of these sites offer some means to edit the wikitext directly. Version history Some wikis keep a record of changes made to wiki pages; often, every version of the page is stored. This means that authors can revert to an older version of the page should it be necessary because a mistake has been made, such as the content accidentally being deleted or the page has been vandalized to include offensive or malicious text or other inappropriate content. Edit summary Many wiki implementations, such as MediaWiki, the software that powers Wikipedia, allow users to supply an edit summary when they edit a page. This is a short piece of text summarizing the changes they have made (e.g. "Corrected grammar" or "Fixed formatting in table"). It is not inserted into the article's main text but is stored along with that revision of the page, allowing users to explain what has been done and why. This is similar to a log message when making changes in a revision-control system. This enables other users to see which changes have been made by whom and why, often in a list of summaries, dates and other short, relevant content, a list which is called a