At the time when you opening Joomla website articles that already you have done, by default the joomla site on a browser will display the url address article is not ending ".html", but will show joomla article with a url with database code php that is relatively longer. This will make Search Engine difficult to find or identify the articles on joomla site (not SEO Friendly) To create the Url to be SEO friendly, you must be customizing SEO Setting in Joomla "Global Configuration. Go to Joomla backend (administration panel), click on the tab: Site > Global Configuration, sign the radio button in yes on SEO Settings.
The next you go to the cpanel, click on public_html and find “.htacces” file. If you find htacces.txt rename it to be ".htacces ". The first time the content of ".htacces" is blank. You must fill with the script below as the content of ".htacces" file, to specify mod rewrite to avoid an error when SEO setting have been activated on global configuration.
Copy the Rewrite Engine script and paste into your “.htacces”. In this way all of the url of joomla website articles will be write into SEO friendly url, that sign by "www.domain_name/category_name/article_title.html". This is more easily for search engine to find all of the articles that you have in your joomla site. For more clearly let's see the article video! Good luck!