S-VHSS-VHS was an improved, backward-compatible version of the VHS standard for domestic video cassette recorders.
It offered substantially better colour fidelity and resolution, with approximately double the number of dots per line (the standard measure of analog video resolution). They could actually represent a better picture than broadcast analog television - in practice, little improvement over standard VHS was visible when viewing material recorded off-air.
To view the better picture, a direct video connection to the monitor was required, ideally a component connection. Older television sets tended not to support this, negating much of the improvement in picture quality.
Home S-VHS decks never became popular outside of Japan, probably mainly due to their high cost, lack of prerecorded content, and the lack of visible performance improvements in playing off-air recording. S-VHS camcorders did become popular for high-end amateur work, as it allowed for at least second-generation copies (necessary for editing) to be made at a reasonable quality.