Definition:Concatenation (Formal Systems)

Definition
Let $\mathcal A$ be an alphabet of symbols.

Concatenation is the process of placing elements of $\mathcal A$ and words in $\mathcal A$ next to each other to form a longer word.

Example
Let $a, b, c \in \mathcal A$.

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

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