The Logo tile for your app listing is often the key to getting noticed. This tile appears on the top left of your listing in Marketplace searches and on the details page of your listing.
Keep in mind that less is more when designing your tile. A large logo with a dark background stands out the best. Check out these three listing in the marketplace and ask yourself which one gets your attention most:
Image tiles should be submitted as a square image in .jpg or .png format. For best results use a size of 256px X 256px. - download a sample logo tile