What is product key in shopify cart api

Question

I am getting back all items response when hitting the shopify cart api, but I am unaware of the key inside each item?

discounted_price: 29900
discounts: []
featured_image: {aspect_ratio: 1, alt: "Tank", height: 533, url: 'https://cdn.shopify.com/s/files/1/0555/6591/0154/p…cts/AK0002W_FIG_W_HAZY_PINE_5120.jpg?v=1651220678', width: 533}
final_line_price: 29900
final_price: 29900
gift_card: false
grams: 0
handle: "form-tank"
id: 41090923692170
image: "https://cdn.shopify.com/s/files/1/0555/6591/0154/products/AK0002W_FIG_W_HAZY_PINE_5120.jpg?v=1651220678"
key: "41090923692170:d9c64b0c0de0189c863835683a0e72ac"

Answer 1

It's a combination of PRODUCT ID: UNIQUE HASH

Basically, any entity must have its unique ID.