Adobe Camera Raw (ACR)
Adobe Camera Raw (ACR for short) is Adobe’s own RAW converter and has been included with Photoshop since CSi was released. It is probably the most widely used RAW converter on today’s market. It is fast and effective, and produces great results for a broad range of camera models. The program is, of course, very well integrated with Bridge and Photoshop. ACR and Lightroom are based on the same core software, and both programs are updated simultaneously when new improvements are introduced. This also means, that what you learn about ACR can directly be applied to the operation of Lightroom.
ACR 5.x only works with Photoshop ...