Certifications Mehadrin and Badatz both point to a higher tier of kosher supervision that goes beyond the basic standard. Mehadrin means the agency followed the stricter opinion at each step, and Badatz refers to a rabbinical court whose certification is usually held at that mehadrin level. Neither one means a regular hechsher is unreliable.
Certifications Glatt kosher means the lungs of a kosher animal were found completely smooth, with no adhesions that needed closer inspection. It is not a different kind of kosher. It is a stricter threshold within kosher meat, and here is what that really tells you at the counter.
Certifications A hechsher is the small symbol a recognized kosher agency prints on a product to show a rabbi supervised how it was made. It is the difference between real certification and a brand simply calling itself kosher. Learning to spot and read one is the single most useful habit for any kosher shopper.
Certifications Chalav Yisrael is dairy watched by an observant Jew from the moment of milking. Chalav Stam is commercial milk produced under government supervision without that presence. Which one you keep is a matter of community custom and your own rav, not a line between kosher and not kosher.
Certifications Kosher certification letters are the small characters next to a symbol, and each one names the product's category. D means dairy, DE dairy equipment, M meat, F fish, and P is the one people misread, because it means Passover and not pareve.
Certifications A kosher symbol is a small trademarked mark, like the OU, OK, or Star-K, that shows a certification agency approved a food as kosher. Learning to read these symbols, and the letters beside them, tells you at a glance whether a product fits your kitchen.