Rare earth elements are essential materials for the manufacture of electronic devices.

An isotope refers to elements with the same atomic number but different numbers of neutrons.

He is an expert in semiotics, and his theories are very profound.

What does this masu symbol mean?

This text is organized using section signs.

Semiotics is the study of signs and symbols used in society and culture.

What does this at sign mean?

The Schläfli symbol is a part of geometry, used to represent the shape of polyhedra.

The bass clef is one of the basic elements of music.

Reading clefs is difficult.