In drupal 4.x, in contents, links are created like this
[url=1]Some text[/url]
So when "Some text" click it open node 1.
Sometime it may link to external url also. like below:
[url=http://www.abc.com/somepage.html] external link [/url]
same thing how can i do it in drupal 7.x
The Drupal bbcode.module adds a BBCode filter to Drupal. This allows you to use HTML-like tags as an alternative to HTML itself for adding markup to your posts. BBCode is easier to use than HTML and helps to prevent malicious users from disrupting your site's formatting.
It uses markup based upon BBCode.