Search Engine Friendly (SEF) URLs are an effective way of improving the experience that customers have on your website at the same time as fine tuning the results that a search engine might generate. Add to the good news that it is a simple one minute job to set them up and it makes sense to enable them.
Have a look at the following two URLs:
Consider the link
yourdomainname.co.uk/index.php?option=com_content&view=category&layout=blog&id=18&Itemid=162 just as an example. These type of links are not so good because they have none of our keywords and it is confusing to read them.
yourdomainname.co.uk/index.php/category-1/28-3-reasons-to-use-long-tail-keyword is good enough, as we can read ...