# What is a more substituted carbon from a less substituted carbon? What does substituted mean?

It just means that there are a different number of non-hydrogen groups on a particular atom. Below, (1) is a tertiary (${3}^{\circ}$), (2) is a secondary (${2}^{\circ}$), and (3) is a primary (${1}^{\circ}$) central carbon.
$\text{ "" "" }$(1)$\text{ "" "" "" "" }$(2)$\text{ "" "" "" }$(3)