TV & CRT pictures must constantly be “refreshed”. Interlace is to refresh every other line once/refresh cycle. Since only half the information displayed is updated each cycle, interlaced displays are less expensive than “non-interlaced.” However, interlaced displays are subject to jitters. The human eye/brain can usually detect displayed images which are completely refreshed at less than 30 times per second. 1
Formerly American Document Management, Glossary of Terms, now 5i Solutions Glossary.