A new law to promote the Welsh language has been unanimously passed by the Welsh Assembly.
The measure makes Welsh an official language in Wales, and obliges public bodies and some private companies to provide services in it.
A language commissioner will be appointed to enforce the measure and to protect the Welsh speakers' rights.
Ministers hailed the vote as a "historic step forward for the Welsh language."
The legislation also establishes a Welsh Language Tribunal and gives individuals and bodies the right to appeal decisions made in relation to the provision of services through the medium of Welsh.
It creates a Welsh Language Partnership Council to advise government on its strategy on the Welsh language.
And it allows for an official investigation by the Welsh Language Commissioner of instances where there is an attempt to interfere with the freedom of Welsh speakers to use the language with one another.
First Minister Carwyn Jones said it had been nearly two decades since any government had introduced legislation solely focused on the Welsh language.
He said: "Although legislation alone is not enough, this measure provides us with some of the tools we need to ensure that the Welsh language can continue to prosper into the 21st Century, alongside the English language."
Plaid Cymru's deputy leader in the assembly, Helen Mary Jones, said: "This is a momentous occasion in the history of the Welsh language.
"The fact that this piece of legislation declares, unequivocally, that the Welsh language has official status in Wales is a giant and historic leap forward."
The longest and most complicated piece of legislation to go before the Welsh assembly, the measure will become law in the new year.
It is part of the One Wales agreement cementing the power-sharing agreement at Cardiff Bay between Labour and Plaid Cymru.