The territory of Judea and Samaria(the "West Bank" )(as well as Gaza), was acknowledged by international law in 1922 to belong to the Jewish People, when The League of Nations ratified the Balfour Declaration. Thus law recognised the Jewish People's inalienable right to be a majority population in the Land which has been its inheritance for three and a half thousand years. The 1947 UN General Assembly recommendation also recognised Jewish territorial rights in The land of Israel.
Jews tolerate Arabs living in Israel, but Arabs want to eliminate the Jewish presence from the Land. Many of the Arabs in Israel are fairly recent immigrants, having come from as far as Egypt, Syria, Sudan to enjoy the economic opportunities which Zionists created in past generations.(Another inconvenient truth.)
Hence the Jewish communities in Judea and Samaria are perfectly legal.
However, for many non-Jews around the world this is an inconvenient truth, therefore they falsely claim that the Jewish communities of Judea / Samaria are illegal.
The Arabs who call themselves "Palestinians" demonise themselves by their actions and words: murder, racism, exploitation of children, embezzlement of donated money, election of Fatah and Hamas, glorification of murder, internecine murder. One could continue for hours.