What are green parties?

Depends on which you are talking about because the Green party is worldwide. The first Green party was established in Tasmania.Green Committees of Correspondence was the first Green party established...

The Green Party's main focus is environmentalism, with other focuses on nonviolence and social justice.

The Green Party (lit. Green Alliance), the green political party in Ireland

One of the political parties in the United States, and similar in mission to many of the worldwide Green Parties, the Greens have been active as a third party since 2001

it is a political party that happens to be more to the "left" and focuses more on helping the enviernment