Magyarization (also Magyarisation, Hungarization, Hungarisation, Hungarianization, Hungarianisation) was an assimilation or acculturation process by which non-Hungarian nationals came to adopt the Hungarian (also called "Magyar") culture and language due to social pressure (often, though not exclusively, in the form of a coercive policy).
The Hungarian Nationalities Law (1868) guaranteed that all citizens of the Kingdom of Hungary (then part of the Austro-Hungarian Empire), whatever their nationality, constituted politically "a single nation, the indivisible, unitary Hungarian nation", and there could be no differentiation between them except in respect of the official usage of the current languages and then only insofar as necessitated by practical considerations. In spite of the law, the use of minority languages was banished almost entirely from administration and even justice. Defiance or appeals to the Nationalities Law, met with derision or abuse. The Hungarian language was overrepresented in the primary schools and almost all secondary education was in Hungarian.
By the end of the 19th century, the state apparatus was entirely Hungarian in language, as were business and social life above the lowest levels. The percentage of the population with Hungarian as its mother tongue grew from 46.6% in 1880 to 54.5% in 1910. Note that the 1910 census (and the earlier censuses) did not register ethnicity, but mother tongue (and religion) instead, based on which it is sometimes subject to criticism.
The Magyarization of the towns had proceeded at an astounding rate. Nearly all middle-class Jews and Germans and many middle-class Slovaks and Ruthenes had been Magyarized. In 1837 the number of Hungarians in the Kingdom of Hungary have risen from 37% to 48% of the total population in 1910.
However, most of the Magyarization happened in the centre of Hungary and among the middle classes, who had access to education; and much of it was the direct result of urbanization and industrialization. It had hardly touched the rural populations of the periphery, and linguistic frontiers had not shifted significantly from the line on which they had stabilized a century earlier.
The process continued also in post-Trianon era. The political and cultural rights offered to interwar Hungary's ethnic minorities were stingier than their equivalents in any other country of East-Central Europe. While anyone who resisted Magyarization was, indeed, subject to political and cultural handicaps, he was not subject to the kinds of civic and fiscal chicaneries (prejudical court proceedings, overtaxation, biased application of social and economic legislation) that some of Hungary's neighbors often inflicted on their ethnic minorities.
Read more about Magyarization: Origin of The Term, Historical Context, Magyarization in The Austrian Empire and Austria-Hungary, Migration, Greek-Catholic Hungarians, Jews, Magyarization in Upper Hungary, Notable Dates, Post-Trianon Hungary