This attribute is strongly recommended as it will improve the listing.
If you have more then one image you can use the "additional_image_link" attribute to include more.
The image should not have any watermarks or any other types of manufacturer or shop logos. The image should be of the model as mentioned in the product name, and other attributes for example colour and size should also be mentioned.
Limit: maximum 2047 characters
No, use one image_link per product. It will be used as the main product picture.
Start with http or https
Follow RFC 3986
Make sure your URL can be crawled
Use stable url
Use verified domain
Replace symbols or spaces with URL encoded entities