Short answers, pulled from the story.
Romanesque architecture is defined by semicircular arches, massive thick walls, sturdy piers, barrel vaults, large towers, and decorative arcading. Buildings typically have clearly defined, regular and symmetrical forms, and the overall appearance is one of solidity and weight compared to the later Gothic style.
Romanesque architecture was predominant in the 11th and 12th centuries, with some scholars dating its range from the late 10th to the 13th century. It emerged nearly simultaneously across multiple countries of Western Europe and eventually developed into the Gothic style.
The French archaeologist Charles de Gerville used the term in the architectural sense in a letter dated the 18th of December 1818, written to Auguste Le Prévost. His friend Arcisse de Caumont then adopted the label in an 1823 public lecture. William Gunn had applied a broader version of the term in English as early as 1813.
The Gothic period brought extensive rebuilding in prosperous regions like England and Portugal, which partly or entirely replaced most Romanesque churches. Southern France, rural Spain, rural Portugal, and rural Italy were less economically active in later centuries, so their Romanesque buildings were not replaced on the same scale.
The Crusades, which ran from 1095 to 1270, moved large numbers of people across Europe including rulers, craftsmen, bishops, abbots, and peasants. This movement created a homogeneity in building methods and spread skills in fortification and metalwork. Returning nobles also funded new church construction as acts of thanksgiving.
Pointed arched ribs first appeared in the transverse ribs of the vaults at Durham Cathedral in northern England, dated to 1128. The earliest pointed vault in France is that of the narthex of La Madeleine, Vezelay, dating from 1130, followed by the east end of the Basilica of St Denis in Paris in 1140.