The two currently most widely-used short-read NGS platforms include:
Illumina sequencing
Illumina uses sequencing by synthesis, detecting light emitted when a growing DNA strand is incorporated with a fluorescently labeled base. Illumina's method involves the use of a proprietary cluster generation process and sequencing with fluorescently-tagged chain terminators. Current read lengths reach up to 2x300 bases, with future technology promising reads up to 30 kb. Run times range from a few hours to two days, producing millions to over 20 billion reads.
Ion Torrent sequencing
Ion Torrent sequencing uses semiconductor technology to detect pH changes caused by hydrogen ions released when a growing DNA strand is incorporated with a base. During a sequencing run, Ion Torrent platforms measure these changes in pH across millions of wells on a semiconductor chip. Read lengths vary by the Ion Torrent system used.
Sequencing by hybridisation (SOLiD), which is another short-read NGS platform, has largely been displaced by Illumina and Ion torrent sequencing.