Twitter was one of the early platforms that came to scale and had a large impact on how social media has shaped up. It is reaching many areas of life. Their role in the political arena has been the most important element among all.
It has played a role in organising political positions and groups and – likely – amplified some political movements. It was purported to play a big role in political movements in the Middle East in the early 2010s. But it came full circle back to its originating country and may have given one particularly active user on the platform the last few votes to become president of the most powerful country. His predecessor was and is still very active on Twitter as well (and has the most followers of all users).