The article introduces a new way to describe languages using substitution expressions, similar to regular expressions. By using union, substitution, and a special type of substitution called substitution star, context-free languages can be characterized. The study shows that linear and regular subfamilies of context-free languages can be obtained by placing specific restrictions on the expressions. The concept of substitution star height is defined, similar to regular star height for regular expressions. The research demonstrates that for any number n, there exists a context-free language with a substitution star height of n.