Responsive Web Design
Responsive web design (RWD) is a design approach that is aimed at creating a website that provides an optimal viewing experience on any device. This is becoming a popular choice for website owners as it only requires the one site, instead of having a separate mobile website. RWD aims to make your website as flexible and fluid as possible so it is pretty much compatible with any device big or small. This is by far the best choice for having a mobile compatible website because not only are you maintaining one website, but having separate sites with the same content can have negative effects on SEO.
If you are happy with your current website and would just like a separate version that is compatible with mobile devices, then a mobile site would be best suited. Your website can detect whether a customer is visiting your website on a mobile device or desktop computer and direct them appropriately. We would still recommend a responsive website over this option.