Forward and reverse, sense and antisense primers
let's take a gene. It's always written from 5' to 3'
there is also a complementary sequence, because DNA is double stranded.
if you wout to do a PCR, you need to enhance both strands, so you need a primer for one strand, called the forward primer, which is the beginning of your gene, and an other primer that will begin the complementary strand (in the 5' end), it's called the reverse primer.
You can call them also sense and antisense. It is the result of antiparallel arrangement of the DNA and important for the sequence-reading preferences of enzymes.
