system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What do steak grades mean?

For e.g MB3+, what does this mean when referring to a steak?
gpt
From USDA website on beef grades:

* Prime Grade is produced from young, well-fed beef cattle. It has abundant marbling and is generally sold in restaurants and hotels. Prime roasts and steaks are excellent for dry-heat cooking (broiling, roasting, or grilling).

* Choice Grade is high quality, but has less marbling than Prime. Choice roasts and steaks from the loin and rib will be very tender, juicy, and flavorful and are, like Prime, suited to dry-heat cooking. Many of the less tender cuts, such as those from the rump, round, and blade chuck, can also be cooked with dry heat if not overcooked. Such cuts will be most tender if "braised" — roasted, or simmered with a small amount of liquid in a tightly covered pan.

* Select Grade is very uniform in quality and normally leaner than the higher grades. It is fairly tender, but, because it has less marbling, it may lack some of the juiciness and flavor of the higher grades. Only the tender cuts (loin, rib, sirloin) should be cooked with dry heat. Other cuts should be marinated before cooking or braised to obtain maximum tenderness and flavor.

* Standard and Commercial grades are frequently sold as ungraded or as "store brand" meat.

* Utility, Cutter, and Canner grades are seldom, if ever, sold at retail but are used instead to make ground beef and processed products.