A dried, roasted preparation of seaweed common to Japanese cuisine. I cannot be clear enough about this, but this only applies to edible forms of seaweed. NOT ALL SEAWEED IS EDIBLE.

Typically, seaweed that is used for nori comes from the pyropia genus (older papers or books may refer to this as porphyra due to taxonomic reclassifications), especially pyropia tenera. That last one is sometimes referred to as gim (a Korean name for a class of ingredients that are used for Korean cuisine) or nori itself. Nori is made from red seaweed; I have not found evidence that green seaweed is used in the preparation of nori.

Nori is used for a variety of dishes. It is used in the preparation of certain types of sushi. If you don’t already know how, it is the vegetative black/brown wrapping around a roll of sushi. Likewise, nori is used in the preparation of onigiri rice balls. Additionally, nori can be used as a garnish for different dishes.

Now, laverbread, made from porphyra umbilicalis. This species of seaweed, found on Welsh coasts, can be used for nori as well. Laverbread, as previously implied, is a Welsh delicacy made from boiled laver (porphyra umbilicalis). Capable of being used for nori, laver can be seen in a lot of Welsh dishes and/or meals.

Now, you saw that I used the name gim earlier. Functionally, they are the same food in most regards. However, the main difference between gim and nori is a matter of what seasoning is used, if seasoning is used. In that context, gim is used for the preparation of kimbap (also known as gimbap, but these are romanizations), bugak, gim-gui (specifically, the sheet form of gim, roasted and treated as a snack or side dish), soup based dishes such as tteokguk, and more.