On a one-day-to-expiry chain, the Greeks behave differently than on longer-dated options. Delta accelerates near the money, gamma spikes, theta decay is brutal, and vega becomes nearly irrelevant in the final hour.

This cluster explains each Greek in plain terms first, then walks through how 0DTE compresses and distorts them. You will learn why a 0.20-delta option can become a 0.80-delta option in minutes when price moves through the strike, and why disciplined traders watch gamma exposure rather than price alone.

Read the foundation lessons first if you are new. Otherwise jump to gamma exposure, which is the single most useful Greek for 0DTE execution.