Welcome to the world of window dressing:

In the world of window dressing there are various often-used terms which at this point deserve clarification.

Head- top of window.
Sill -the window board.
Reveal -side walls to window recess.
Fabric weight -thickness of weave.
Sheer -very fine fabric: cheesecloths, muslin, nets and laces.
Heading tape- tape at top of curtains/fabric blinds for gathering and inserting hooks.
Gathering -tightening of heading tape to pleat or ruffle the fabric.
Track/pole/rail- support for curtains, blinds and valances, in plastic, timber or metal.
Tie-back -shaped fabric or decorative rope securing curtains in drapes. Ornamental metal pins (clips) may also be used to hold back fabrics.
Swag and tail- decorative draping of fabric.