Wick (Shadow)
The thin line above/below a candle body, showing the high/low tested before the close.
Long upper wick = price pushed up then sold off. Long lower wick = price pushed down then bought back. A series of wicks at the same level is price telling you where rejection is happening.
Related
Learn to actually use Wick.
Definitions are the easy part. The free first five modules put this on a real chart and make you do the work. No card required.