Side-by-side 3D format
Side-by-side 3D format (SBS 3D) is a method of providing a 3D video stream with the two images (one for each eye) placed horizontally across the image as transmitted. It has two sub-varieties, Half SBS and Full SBS.
A half SBS stream compresses the horizontal dimension of each of the two images in order to fit the two images in the width and height of one normal 2D image, thus maintaining compatibility with any non-3D-capable devices or software involved in the production, transmission, and storage of the video data, which simply treat it as a normal stream of the given width and height. On non-3D devices it would appear as two squashed images side by side, with an altered aspect ratio, but a 3D device would decode it by splitting the two images and presenting them in alternate frames at full width (but half the horizontal resolution).
A full SBS stream keeps both images at full resolution, but requires a frame size of twice the width of a single image, which might not be displayable on non-3D devices expecting the normal frame width. As with half SBS, a 3D decoder presents the halves in alternate frames. In both systems, the effective frames-per-second for each image is half of the frames-per-second of the stream.
Viewing of this format in 3D would involve wearing special glasses that alternately blank out each eye's view at the appropriate frame rate so that the left and right eyes see the frames intended for them.