A tussenvoegsel ( ) in a Dutch name is a family name affix positioned between a person's given name and the main part of their family name. There are similar concepts in many languages, such as Celtic family name prefixes, French particles, and the German von. The most common are , e.g. Vincent van Gogh meaning "from"; and , e.g. Greg de Vries, meaning "the". A forms an integral part of one's surname; it distinguishes it from similar Dutch surnames, e.g. Jan de Boer compared to Albert Boer; Frits de Kok compared to Wim Kok.
originate from the time that Dutch last names officially came into use. Many of the names are place names, which refer to cities, e.g. Van Coevorden ("from Coevorden"), or geographical locations, e.g. Van de Velde ("of the fields"). The following list of includes approximate translations, some of which have maintained their earlier meaning more than others.
In the Netherlands, these are not included when sorting alphabetically. For example, in the Dutch telephone directory, "De Vries" is listed under "V", instead of "D". Therefore, in Dutch databases are recorded as a separate data field so as to simplify the process of locating it. Sorting by would result in many names being listed under "D" and "V". In Dutch grammar, the in a surname is written with a capital letter only when it starts a sentence or is not preceded by a first name or initial. So referring to a professor named Peter whose surname is "de Vries", one writes "professor De Vries", but when preceded by a first name or initial it is written using lower case, such as in "Peter de Vries" or "P. de Vries".
In Belgian Dutch, or Flemish, surnames are collated with the full surname including . "De Smet" comes before "DeSmet" in a telephone book. Although French family names commonly also use , those are frequently contracted into the last name, e.g. turning Le Roc into Leroc, or La Roche into LaRoche, and thus explaining the collation preference. In contrast to Dutch orthography, Belgian always keep their original orthography, e.g. , , or .