The answer isn't the same for everyone. A multivitamin generally includes both vitamins and certain key minerals. There are different multivitamins based on age and gender; however, the differences are generally minimal. For those who are on a restricted diets such as during active weight loss or food elimination diet, I do recommend a good quality multi-vitamin/mineral at least in the short term. However, there are some situations where a multi-vitamin/mineral may be more critical. These includes during pre-conception and pregnancy, post-bariatric surgery and recovering from certain disease states (celiac, inflammatory bowel disease) where malabsorption of nutrients may be compromised. A multi-vitamin/mineral is generally a very safe choice because it doesn't contain mega-doses and can help prevent deficiencies. I also find it beneficial to use a micronutrient test to take a more targeted approach to nutritional supplementation as there is no one-size-fits-all approach.