We first look for similar ingredients that you have added to your shopping list in the past and use the grocery category from the most recently updated ingredient. If we can't find a similar ingredient on your shopping list, we then look at everyone else's use of the ingredient and place it in the most popular category.
For example: if you move ketchup into your condiments category, Plan to Eat will automatically place all future instances of the ingredient ketchup in the condiments category until you move it elsewhere on your list.
If you don't like where the ingredient was placed on your shopping list you can easily drag it (or multiple ingredients) to a different category on your list. You can also edit an individual ingredient using the pencil icon and update the category. Then the next time that ingredient appears on your shopping list it will automatically be placed in your selected category for that ingredient.
You can also customize the categories on your shopping list. This video will show you how to set up your categories and move items from one category to another: