Cooking
Cooking is one of the skill points to be gained in both The Sims and The Sims 2.
Building cooking skill
In The Sims, cooking skill is built by studying from a bookcase. In The Sims 2, bookcases are an option but so are watching the Yummy Channel, using the toy oven (for children), using the Schockolade 890 career reward object, or simply by preparing food.
Implications
Career-wise, cooking is most relevant - obviously - to the culinary career path. At home, sims with higher cooking skill (or eating food prepared by sims who have) benefit from better satisfaction of hunger needs, less risk of starting fires, and in TS2 also a better choice of recipes.