Short answers, pulled from the story.
Islamism is a range of religious and political movements that believe Islam should influence political systems. Its proponents hold that Islam is innately political and that Islam as a political system is superior to communism, liberal democracy, and capitalism in achieving a just society. Followers, also known as al-Islamiyyun, emphasize the implementation of sharia, pan-Islamic unity, and the creation of Islamic states.
Central figures of 20th-century Islamism include Rashid Rida, Hassan al-Banna who founded the Muslim Brotherhood, Sayyid Qutb, Abul A'la Maududi, Ruhollah Khomeini who founded the Islamic Republic of Iran, and Hassan Al-Turabi. Rashid Rida is widely regarded as one of the ideological forefathers of the contemporary Islamist movement.
Islamism first appeared in English as Islamismus in 1696 and as Islamism in 1712, where it simply meant the religion of Islam rather than an ideology. By 1938 it had virtually disappeared from English usage, then returned with a political meaning after the Iranian Islamic Revolution of 1978-79.
The Caliphate was abolished by the Turkish National Assembly in March 1924, after the Grand National Assembly of Turkey abolished the Ottoman Sultanate on the 1st of November 1922. This shocked the Sunni clerical world and led many to present Islam as a modern socio-political ideology, giving rise to ideologues like Rashid Rida and Maududi and organizations such as the Muslim Brotherhood.
Starting in the mid-1970s, Saudi oil money funded the Islamic resurgence, with estimates that the Saudis funnelled over 100 billion US dollars between the 1960s and 2016 to spread Wahhabi Islam. The money paid for more than 1500 mosques over fifty years, along with madrassas, scholarships, and satellite campuses for Al-Azhar University, promoting a strict Wahhabi or Salafi interpretation.
Shia Islamism, associated mainly with Ayatollah Ruhollah Khomeini, has been described as more leftist and more clerical than Sunni Islamism. It was more leftist in its pre-revolution propaganda about exploitation of the poor, and more clerical afterward, with clerics controlling power under the concept of Velayat-e Faqih, the guardianship of the Islamic jurist.