Google has already announced that web site speed is one of the ranking factors in their ranking algorithm. Therefore all webmasters are trying to improve their web site loading speed as much as possible.
There are lot of CDN providers on the market now. If you are searching for a reliable CDN for a cheap price then I recommend you MaxCDN (this is not an affiliate link). MaxCDN is a powered by NetDNA which is one of the leading CDN provider. MaxCDN has servers located in many countries.
This video from MaxCDN will give you more information about how CDN works and how MaxCDN helps to Speed up your website.