The best way to link to articles that reside within your own Joomla website is to use the internal linking system. This system uses PHP and the ID number of the article. It may seem convoluted, but it it a better method that typing in the live URL to the page. In many cases this method will keep the link unbroken if you move the article to a new category or change the title.

Use the link icon in JCE Editor

JCE Editor Link Dialog Box

If you use JCE Editor, there is a link button in the dashboard. It will open up a dialog box where you can select from  Contacts, Content, Menu or Weblinks.

If you used a Menu to create a Single Article Menu Item for the page you can navigate to that page by clicking on the Menu Icon.

If your article is not part of a Single Article Menu Item, you can click on the Content icon and navigate to the article that way.

Either method will fill in the URL box at the top with the correct form for the link to that article and create the <a href="/">...</a> HTML code for the link.

The url will look something like:

index.php?option=com_content&view=article&id=2:what-is-joomla&catid=9:home&Itemid=101

or

index.php?option=com_content&view=article&id=2&Itemid=101

Using this link icon interface allows you to do a number of other actions, like if you want to open the link in a new browser window, if you want to link to anchor tags on the same page, add classes or inline styles to the link, or create a popup dialog box. It also allows you to find images, pdf documents and other items.

Find out more about the features of the JCE Editor Link dialog box: JCE Editor Creating Links

Use the Article button below the JCE Editor Text window

You can also link to other articles on your site from JCE Editor by clicking on the Article button below the text editor. This will bring up a list of all the articles that you have for the site.

This interface that you get with the Article Button does not have all of the features that you get with the link icon in the dashboard. 

Use the TinyMCE Text Editor

If you are using the TinyMCE text editor that comes with Joomla, it is best to use the Article button that sits below the text editor.  It allows you to select from the other articles on your site by their title. it will place a link like this into the HTML code for the link.

index.php?option=com_content&amp;view=article&amp;id=2&amp;catid=9&amp;Itemid=101

The link icon allows you to type in a URL, but will not display the articles with your site.

What will the visitor see?

The user doesn't actually see the code behind the link.

If you have SEO friendly URLs enabled in your Global Configuration, the user will see the SEO friendly URL if he hovers over the link or copies it. The URL that shows up in the browser if he does click on the link will be the SEO friendly link.

If you don't have the SEO friendly links, the URL for the new page will be the PHP code for that page that includes the ID number for the page.