The feature was introduced in Photoshop 7.0 as Version 1.0. Since then, new major versions of Photoshop come with a new major version of ACR. Each version of Photoshop is limited to a certain version of ACR (typically the last minor ACR version released before a new major version of PS). ACR is also available for many other Adobe graphics applications. Lightroom has built-in RAW format support which coincides with ACR.
As of June 2020, the current version of ACR is version 12.3.
Alternatives for ACR
Because older versions of ACR may not support newer cameras, Adobe recommends upgrading to the latest version of Photoshop. Adobe also provides a free Adobe DNG Converter for Macs and PCs, which "enables you to easily convert camera-specific raw files from more than 350 cameras to the more universal DNG raw format."
Camera manufacturers often provide tools that allow their raw format to be converted to an intermediate format that can be opened by Photoshop (typically TIFF). Some manufacturers even provide their own image editors. The manufacturer's raw format codec is not sufficient for editing; it is meant only for viewing using the OS' native image viewer.
On Windows computers, a freely-available third-party program called IrfanView can be used in cases where a manufacturer's utility is difficult or impossible to find. IrfanView by itself doesn't open raw format files, but the its plugin can be easily added to provide support.
On Mac OS computers, raw format support is provided by Apple and is updated with each new OS release. Their support page can be consulted for details. Apple Photos, Aperture, and iPhoto are Lightroom-like programs that can convert raw images from supported cameras.
For Macs and PCs, RawTherapee is another free option which not only opens RAW files, but is a complete RAW editor with an extensive list of features.