This is an app to replace your paper shopping lists. No more paper, no more pencils, no more having to remember precisely what you need.
Type what you need on the bottom and hit add. Now you have a list of all the things you need. Go to the store. As you pull items off the shelf, you can tick off the items on the right side of the item. Once you pay for the items, tap 'Buy' to remove those items from your list. Easy peasy. Hitting 'buy all' clears your entire list.