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 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.