Support and resistance: read zones, then test the idea
Support describes an area where declines have previously met buying interest. Resistance describes an area where advances have previously met selling interest. They are observations about past trading, with no guarantee that the same response will return.
Why a zone can be more useful than a line
Suppose an unnamed stock stops falling at $48.80, $49.10 and $48.95 on separate sessions. Calling $49 a reference area preserves the observation. Treating $49.00 as a mechanically exact boundary adds precision the data did not provide.
Now suppose the next session trades at $48.70 and closes at $49.30. Whether that counts as a break depends on the rule you wrote beforehand: an intraday crossing, a closing price, or something else. Changing the definition after the close makes the record difficult to evaluate.
A small research exercise
Choose a chart interval and mark a zone using information available up to a fixed date. Save that version. Move forward several sessions and record what happened, including failures. Keep the definition unchanged for the exercise.
An organised TC2000 chart workspace helps preserve those snapshots. The record should include the date, interval, price-adjustment setting and reason for selecting the zone.
Avoid drawing a fresh line for every turn. Enough lines can explain nearly any historical chart. Instead, decide in advance how many observations you require and what would disprove the original description.
Company announcements and changes in market conditions can overwhelm a previously observed area. If the explanation relies entirely on a line having worked before, you still have to assess liquidity, possible loss and the next scheduled event.