In the topic How to Import Products in Magento 2, there is Images File Directory field of the path leading to your product image file. To explain for the presence of the Images File Directory field, Magento has its own directory structure for product images which is alphabetically organized and the path to the specific image is included in the import product file. Actually, you can upload the image file on Magento server or external server after login with the correct credentials that has the permission to manage the Magento folder on the server. It is easy to see that there are two step to Import All Products with Images and I will also demonstrate you two ways to import your product images : with Local Server and with External Server.
pub/media/import. You can use a different folder as well on the Magento server, as long as the path to the folder is specified during the import process.
base_image, small_image, thumbnail_image, or additional_images). Make sure the relative path to the import directory is included before each file name. For example:
/pub/media/import/image.jpg. The CSV file needs to include only the SKU column and the related image columns. If you want to import multiple images for a single SKU, insert a blank row below the SKU, and enter the additional image file names in the appropriate columns.
base_image, small_image, thumbnail_image, or additional_images). For example:
Process as same as the step 2 of the first method.
Ref: Magento 2 user guide
It comes to the end of tutorial: How to Import All Products with Images in Magento 2.
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