They discounted dozens of products and saw great success — so much success, they doubled it to two days. Then four days. And now, it's no longer just Amazon Prime Day — it's the biggest sales week of the entire summer,

Target will match a Prime Day price as long as the item in question is identical to the one listed at Amazon — down to the model number and color. Target will ask for proof of the lower price at Amazon in the form of a direct listing or ad. No, screenshots and pictures don't count.

Amazon Prime Day officially got underway Tuesday, with the summer sales event slated to last through July 11. Competitors Target and Walmart are also holding multi-day sales events.