Iran's political landscape is broadly divided into two groups: hardliners and reformists. Each group contains a range of more moderate and more conservative forces.
The hardline camp is largely made up of loyalists of Mr Mahmoud Ahmadinejad, President Hassan Rouhani's predecessor, who raised tensions with the US and suppressed dissidents during his two terms in office.
Reformists first rose to power with the 1997 election of President Mohammad Khatami, followed by 2000 parliamentary elections that sprang a reformist majority in Parliament for the first time. The reformists stood for an easing of Islamic social restrictions, a greater public voice in politics and better ties with the international community.
However, in the next parliamentary elections in 2004, the reformist candidates were largely barred from running. With Mr Ahmadinejad's election victory in 2005, they were shut out of politics for nearly a decade until Mr Rouhani was elected in 2013.