A variety of models have been employed to illustrate how Uralic languages are related to each other.
The traditional model is the so-called family tree. The family-tree model was put forward already in the 1800s to make it easier to understand how the Indo-European languages are related.
A family tree is a clear way of illustrating the relatedness between languages. The closer the branches representing the different languages are to each other, the more closely related to each other the languages.
The family tree has even been regarded as too simple a model of the evolution of languages for reasons including that the traditional family tree makes the splitting of dialects into languages look like a once-off occurrence, although in fact the process of language separation takes place over a long period of time, and sometimes languages that have evolved in their separate ways may also become closer to each other again.
This is why linguists have also made efforts to illustrate the relatedness of languages by means of many other models. Recent decades have also seen different versions of the family tree of the Uralic languages.
Häkkinen, Jaakko 2009: Kantauralin ajoitus ja paikannus: perustelut puntarissa [Dating and locating Proto-Uralic: Weighing the evidence]. Suomalais-Ugrilaisen Seuran Aikakauskirja. Journal de la Société Finno-Ougrienne 92. Société Finno-Ougrienne – Finno-Ugrian Society, Helsinki. http://www.sgr.fi/susa/92/hakkinen.pdf
Häkkinen, Jaakko 2009: Uralilaisen sukupuun kehitys [The development of the Uralic family tree]. http://docplayer.fi/29554350-Uralilaisen-sukupuun-kehitys-jaakko-hakkinen.html
Kulonen, Ulla-Maija 2002: Kielitiede ja Suomen väestön juuret [Linguistics and the roots of the Finnish population]. In Ennen, muinoin: miten menneisyyttämme tutkitaan [Former Times: How our Past is Studied]. Finnish Literature Society.