It is a computer model of a virus depicting the sequence of a covid (RNA) virus. Let's say the alphabet A-Z represents the entire viral genome sequence. They look for a remnant of it, say C thru P and call it delta. For the 'new' strain they look for D thru Q and call it whatever. On and on it goes ad infinitum. The PCR is a fraudulent test and many people have some old remnants of RNA from a cold or whatever. They adjust the cycles of amplification until they gain a positive.