A pullback is a temporary reversal against the dominant direction within an otherwise-trending market. In an uptrend, price retraces lower to a moving average, prior support, or a measured retracement (Fibonacci levels are common reference points).
Pullback strategies tend to be higher win rate but tighter R than breakouts, because the entry is closer to a logical stop (just under the moving average or support). 50–65% win rates with 1.0–1.5 average R are typical patterns in trader journals.
The hard part is distinguishing a pullback from a trend reversal in real time. The same chart pattern that looks like a buyable pullback at the moving average looks like a failed pullback after price slices through. The 'invalidation' is the moving-average break itself.
Combine with breakout exits: pullback entry, partial profit at the next swing high, trail the remainder. Combinations like this are what make journal review worthwhile — your historical data shows whether your specific take-profit rules captured the move or left it on the table.