Organic foods are foods grown without the use of pesticides, herbicides, and chemical fertilizers. When foods are not grown organic the residue from these toxic substances remain on the foods. A quick rinse is not enough to rid your food of these chemicals. In fact, even scrubbing your foods with warm water and soap does not totally "clean" up your produce.
Not all non-organic food need the same degree of chemical application for the growing process. Some produce needs less and some need more. The dirty dozen are ones that are grown with more pesticides, herbicides, and synthetic fertilizers. For these foods you should seek out the organic variety. On the flip side the clean fifteen are foods that do not need a lot of chemicals and therefore you can afford to buy these as non-organic.
1) If you are pregnant or trying to conceive.
2) Are a young child.
I would also recommend that if there is a particular food that you eat on a regular basis source the best quality organic variety that you can. Whether it is coffee, apples, spinach, or coconut milk, if there is a food you eat everyday make sure it is the best!
I hope this helps explain organic eating in a simple way. It doesn't have to be confusing nor should it be something you should stress about. If you can eat organic then great! Everyone should strive for this goal. If you are in a point in your life where it is not an option for you, that is ok. Focus on eating whole fresh foods and you are off to a good start.
Live Your Best Life!