1-Knitted loop & loop shape:
A kink of yarn that is intermeshed at its base i.e. when
intermeshed two kink of yarn is called a knitted loop. A
knitted loop is a basic part of knit fabric

2-Needle loop:
The loop is the simplest unit of knitted structure. It is
formed by the top arc & the 2 logs of the weft knitted loop.

3-Sinker Loop:
The yarn portion that connects two adjacent needle loops
belonging in the same knitted course. Sinker loop is specially
the portion of bottom arc.