OGSA-DAI (Open Grid Services Architecture - Data Access and Integration) provides an extensible software framework allowing data resources, such as files, relational and XML databases, to be exposed through Web services acting within collaborative Grid environments or, more modestly, in stand-alone mode. OGSA-DAI may be deployed to WSRF-based platforms, such as the Globus Toolkit 4, as well as non-WSRF based ones, such as the UK OMII Server or standard versions of Tomcat and axis. Regardless of the platform, the core functionality provided remains the same. OGSA-DAI allows data resources to be accessed and integrated into the main infrastructures presently being used to construct Grids. OGSA-DAI provides a number of optimisations that reduce unnecessary data movement by shifting work to the Web service and encapsulating multiple client-Web service interactions into a single one, and allows for functionality to be added or customised based on the application. OGSA-DAI is widely used and is available from www.ogsadai.org.uk. It is also bundled with the OMII-UK and Globus Toolkit distributions. This paper gives an overview of what OGSA-DAI is, how it works, presents some usage scenarios, and outlines future enhancements.