Knit fabric
A fabric made of interlocked loops of yarn, which stretches and recovers its shape.
Jersey, rib, interlock, fleece and French terry are knit fabrics. Their stretch allows less ease and fewer darts, but each fabric stretches by a different percentage, so the pattern has to be made for the stretch of the fabric that will be used. Knit edges do not fray, but they tend to curl, and they are sewn with stretch stitches.
Example
A t-shirt pattern for a cotton jersey with good crosswise stretch can be cut smaller than the body, because the fabric stretches to fit.