A bull call spread is a vertical spread where you buy a call at a lower strike and sell a call at a higher strike, both expiring the same month.
Apple at $150:
Maximum profit: $10 - $5 = $5 per share ($500) if stock closes above $155. Maximum loss: $5 per share ($500) if stock closes below $145. Breakeven: $150 ($145 + $5 cost).
Maximum Profit: Width of strikes minus net cost
Maximum Loss: Net cost paid
Profitable Zone: Between breakeven and max profit at expiration
Use when you're moderately bullish but want to reduce cost and risk. The sold call offsets the bought call premium.
Related: Bear Call Spread, Bull Put Spread, Vertical Spread