"Serging" is yarn wrapped around the edge of the rug and it protects and hides the raw edge of the rug. It's formal serging is about 3/8" to 1/2" wide.
Micro Serge
"Micro-Serging" is about a 1/4" wide.
Hand-Serge
Serge is accomplished by hand and is about 3/8" wide.