Markdown is a lightweight markup language that is designed to be converted to HTML. It is often used for formatting readme files, writing messages in online discussions, and creating rich text using a plain text editor. While Markdown is designed to simplify many of the common formatting tasks, its features are sometimes limited when compared to direct HTML coding, especially when specific attributes like target for links are needed.

Understanding target="_blank" in HTML

Before we tackle how to achieve this in Markdown, let's first understand what target="_blank" does in HTML. This attribute when used on an <a> tag, specifies that the link should open in a new browser window or tab. It is commonly used to ensure that the user stays on the original page, thus improving site retention or for linking to external sites without navigating away from the original content.

Markdown's Native Capabilities

Markdown, in its basic form, has no syntax to handle HTML attributes like target. The traditional syntax for a link in Markdown is simple:

[link text](http://url.com)

However, to include the target="_blank" attribute, you must resort to using straight HTML in your Markdown:

<a href="http://url.com" target="_blank">link text</a>

Using straight HTML is fully supported in most Markdown processors, and it will behave as expected in HTML rendering. However, it loses the simplicity and readability that Markdown aims for.

Extensions and Variants

Some implementations of Markdown, such as GitHub Flavored Markdown (GFM), Markdown Extra, and others have added additional features that extend the basic capabilities of standard Markdown. These extensions sometimes include support for additional attributes in links or other elements, either through an extended syntax or automatic behaviors.

Summary of Key Points

Practical Considerations

Using HTML within Markdown documents can arguably reduce readability and simplicity — the core features that make Markdown popular. Therefore, it's crucial to decide based on your use case whether sticking to plain Markdown or mixing HTML meets your needs more effectively. If the usability benefit of having target="_blank" (keeping users on your page while opening new links) outweighs the markdown purity, then using HTML is the way to go.

Tips for Usage

1. Consistency: Keep your use of raw HTML within Markdown files as consistent as possible to maintain readability.
2. Validation: Always validate your HTML syntax when mixing it with Markdown to avoid rendering issues.
3. Compatibility: Test your Markdown on all platforms where it will be used (GitHub, GitLab, Bitbucket, etc.) as their rendering engines may differ.

Extensions and Tools

For those using static site generators like Jekyll or tools like Pandoc, plugins or filters can often automatically add attributes like target="_blank" to all external links, combining ease of Markdown with the functionality of HTML.

In summary, while Markdown itself doesn't support target="_blank", using straightforward HTML or opting for an extension that supports this feature can achieve the desired effect. Each approach has its pros and cons, and the choice depends largely on the specific needs and constraints of your project.