Tables are supported only in certain flavors of Markdown, including Markdown Extra and Github Flavored Markdown, but not in the original Markdown syntax or in CommonMark.

Markdown tables are also not supported on Stack Exchange sites (with the exception of the Documentation beta).

• Some implementations of Markdown, such as Stack Exchange's, support spoiler quotes, which look the same, but hide the content of the quote until you click on it.

The syntax for images is the same as that for links, but with an exclamation mark ! in front of the text (which is used as alt-text).

Variations of Markdown with differing syntax are called "flavors." Markdown flavors are listed at https://github.com/jgm/CommonMark/wiki/Markdown-Flavors.

A Markdown flavor can be implemented in various programming languages and software applications. Libraries that implement a Markdown parser are listed at https://github.com/markdown/markdown.github.com/wiki/Implementations and https://www.w3.org/community/markdown/wiki/MarkdownImplementations.

Several Markdown flavors, and the differences between them, are documented at http://flavoredmarkdown.com.

To test and compare Markdown code in many different flavors, and implementations of those flavors, you can use the online tool Babelmark.