The action attribute of the form element defines the URL (or URI) where the form data should be sent after submission. This can be a URL of a server-side script (like PHP, Python, etc.) that processes the form data and sends a response back to the user. The choice of where to send the data is crucial as it determines how the data will be processed and handled on the server side. 

In HTML, a description list is represented using the

tag. Within this list, the

tag is used to denote the term, and the

tag is used for the corresponding description. Description lists are useful for things like glossaries or key-value pairs. 

The

tag is not directly associated with tables. Instead, it's used with the

element to provide a visible heading for its content, making sections of content expandable and collapsible. This can improve user experience by letting users choose which sections they want to see, reducing information overload. 

The

element is utilized to group the body content in a table and works as a container for one or more

elements (table rows). While

defines a row, the

helps in structuring the table and can be particularly useful when working with styles and scripts, as you can apply styles or perform actions on this grouped content. 

The target attribute specifies where to open the linked document. When set to _blank, it ensures that the linked document is opened in a new tab or window. It's often used when linking to external sites to keep the original page open in the background.