Capellini with its diameter between 0.85 mm and 0.92 mm is a very thin variety of Italian pasta

Pasta

Pasta is a staple food of traditional Italian cuisine, now of worldwide renown. It takes the form of unleavened dough, made in Italy, mostly of durum wheat , water and sometimes eggs. Pasta comes in a variety of different shapes that serve for both decoration and to act as a carrier for the...

. Like spaghetti

Spaghetti

Spaghetti is a long, thin, cylindrical pasta of Italian origin. Spaghetti is made of semolina or flour and water. Italian dried spaghetti is made from durum wheat semolina, but outside of Italy it may be made with other kinds of flour...

, it is rod-shaped, in the form of long strands.

Capelli d'angelo (kaˈpelli ˈdandʒelo, literally angel hair) with a diameter between 0.78 and 0.88 mm is an even thinner variant of capellini. They are often sold in a nest-like shape.
Capelli d'angelo has been popular in Italy since at least the 14th century. As a very light pasta, it goes well in soups or as "pasta asciutta" with a seafood other light sauces.