Foundations
Reading the Greeks without panic
Delta, theta, vega, gamma. Four numbers, four jobs. None of them require math beyond fifth grade once you see what they actually answer.
The Greeks are sensitivities. Each one answers a question of the form "if X moves by one unit, how much does my option price move?" That is the entire concept. The Greek letters are just labels.
Delta
answers: if the stock moves $1, how much does my option move? A 0.30 delta call gains roughly $0.30 when the stock gains $1. It also has a rough 30% chance of finishing in the money. Two birds, one number.
Use delta as your strike-picker. Want a high probability trade? Sell a 0.20 delta option. Want a directional bet with more punch? Buy a 0.50 delta. Delta is the fastest way to translate "how confident am I" into a strike.
Theta
answers: how much does the option lose to time, per day? A short call with $0.05 of theta makes you $5 per contract per day, all else equal. Sellers love theta. Buyers hate it.
Theta accelerates as expiration approaches. That is why credit sellers love the 30 to 45 DTE band. Plenty of theta left to collect, but the gamma risk has not gone vertical yet.
Vega
answers: how much does the option move per 1 percentage point change in IV? Long options are long vega. Short options are short vega. After earnings, IV usually crushes, which helps short-vega trades and hurts long-vega ones.
Gamma
is delta's second derivative. It answers: how fast will my delta change as the stock moves? High gamma means even small price moves swing your P&L hard. Gamma spikes near expiration on at-the-money options, which is why professional traders close trades by 21 DTE.
What to do next
Open the trade detail page on any setup. Find the Greeks section. Read each line out loud as a sentence: "this trade gains $X per $1 stock move, loses $Y per day, gains $Z per 1% IV move." Once the Greeks become sentences, they stop feeling like math.