Protein requirements vary depending on your age, gender, level of physical activity, special health conditions, and pregnancy. The DRI (Dietary Reference Intake) is 0.8 grams of protein per kilogram of body weight, or 0.36 grams per pound. Individuals who workout especially weight training typically need a bit more 1.0-2.0 gram per kilogram body weight. I typically recommend 1.2g/kg for my clients when starting out.
Meat, fish, poultry, beans, nuts, dairy foods and lentils are among the best sources of protein.