The product bulk upload file can be a CSV, Excel or XMLand it should contain at least the product name and the price.
We recommend that you assign each product with a unique identifier that can be either a Product ID or an SKU and that does not change over time. In order to automatically update the products (prices, images, etc.) you just have to make a new import, because the system will match your catalog products with the ones from the bulk upload file by using the unique identifier assigned to each product.
Listed in: Catalog settings