Like almost any living language, Finnish exists in several different variants. “Standard Finnish” is what grammars, dictionaries, and textbooks mostly deal with, and it is taught at schools and used in public presentations and formal occasions. It is hardly anyone’s native language, though.
In the old days, people learned a local language version, or “dialect”, as their native language. We will cover some main features of major dialects in this book. In urban areas, and even more generally, differences between dialects have partly been leveled down. Especially young and urban people tend to use “common spoken Finnish”, which differs from standard Finnish in several ways. It might even be called standard spoken Finnish, even though it lacks all formal standards.
Later in this book, basic deviations of standard spoken Finnish from standard (written) Finnish and some features of dialects of Finnish will be described. Standard spoken Finnish is what you can expect to hear in informal discussions between people from different areas of Finland or people living in the Helsinki area, where the use of dialectal features is uncommon. The language used e.g. in TV and radio broadcasts tends to be standard spoken Finnish in informal programs, standard Finnish in news, interviews of officials, etc., though spoken language features may be used intentionally or unintentionally in them. Standard spoken Finnish can be characterized as the common spoken language in Helsinki, originally reflecting some dialectal features, but now recognized as rather neutral with respect to dialects. Especially radio, TV, and to some extent films made it known and imitated in other parts of the country.
In addition, there are local slangs and professional jargons. These language forms are not discussed much in this book.