A converter for HDMI to SCART or SCART to HDMI is an item you need when you want to play the old European SCART format discs on modern players in the UK. SCART is a format and standard using a 21-pin connection for connecting analogue based audio-visual equipment.
Although newer technology has replace it, devices using this format are present in many people's collections.
HDMI or high definition multimedia interface is a standard for digital player to computer interconnection, and so an HDMI-SCART converter can allow playing SCART based items on your computer or other media player, converting the files from one format to the other. Most converters work with DVD, Blu-ray, and other modern formats for video and audio files.