Short answers, pulled from the story.
According to Clayton Thyne and Jonathan Powell's coup dataset, there were 457 coup attempts from 1950 to 2010. Of these, 227 (49.7%) were successful and 230 (50.3%) were unsuccessful. Africa and the Americas accounted for the largest shares, at 36.5% and 31.9% of global coups respectively.
A coup d'état is a broad term for any illegal seizure of state power by insiders, while a putsch specifically denotes the political-military actions of a minority reactionary group. The term putsch was first coined for the Züriputsch of the 6th of September 1839 in Switzerland, and was later applied to events such as Adolf Hitler's 1923 Beer Hall Putsch in Weimar Germany.
A self-coup occurs when a leader who came to power through legal means uses illegal means to stay in power. The 2021 Tunisian self-coup, in which President Kais Saied deposed Prime Minister Hichem Mechichi, is a recent example. Kais Saied remains in power in Tunisia as a result.
The coup trap is the phenomenon in which the cumulative number of past coups in a country is a strong predictor of future coups. A 2014 study of 18 Latin American countries found that establishing open political competition is the primary mechanism for breaking out of the trap and reducing cycles of political instability.
Coup success depends heavily on the plotters' ability to convince others that the attempt will succeed, a manufactured perception of fait accompli. Key operational requirements include control of communication hubs, political centers, and military bases, as well as the neutralization of loyalist forces. Coups most commonly fail due to poor communication, hesitance, or the inability to neutralize the national leader or seize media quickly enough.
Coups still mostly perpetuate authoritarianism, but the post-Cold War period has seen a shift. During the Cold War from 1950 to 1990, only 12% of successful coups in dictatorships led to democratization within two years. From 1990 to 2015, that figure rose to 40%. About half of all coups in dictatorships across both periods installed new autocratic regimes, which tend to be more repressive than their predecessors.