Concatenation

Concatenation is the joining of two or more strings into a larger string. Usually this operation is common enough to warrant an operator, which is often '+'; although the addition sign can be misleading as concatenation is order-dependent unlike numerical addition.

Concatenation is not particularly efficient in languages with immutable strings, and can cause performance and memory usage problems if many strings need to be joined into a larger one. For this reason, these languages will usually provide a string joining function that can take a list or array of strings and efficiently concatenate them.