Definition:Concatenation (Formal Systems)

Let $$\mathcal{A}$$ be an alphabet of symbols.

Concatenation is the process of placing elements of $$\mathcal{A}$$ next to each other to form a string.

For example, let $$a, b, c \in \mathcal{A}$$.

Then concatenating $$b$$ to $$a$$ results in the string $$ab$$, and concatenating $$c$$ gives the string $$abc$$. Concatenating $$b$$ then gives $$abcb$$.

Concatenating $$aba$$ to $$aabcba$$ gives the string $$aabcbaaba$$.

Linguistic Note
The word concatenation derives from the Latin word "catena" for "chain". However, a string is not to be confused with a chain.