Short answers, pulled from the story.
Don D'Ammassa argues that danger must be the central focus for a work to qualify as true adventure fiction. He cites Charles Dickens's novel A Tale of Two Cities as a prime example because its protagonists face constant threats of imprisonment or death throughout the narrative.
American pulp magazines dominated popular fiction between the Progressive Era and the 1950s. Publications such as Adventure, Argosy, Blue Book, Top-Notch, and Short Stories specialized heavily in adventure fiction during these peak years.
Johann David Wyss published The Swiss Family Robinson in 1812. This work marked one of the earliest appearances of adventure stories written specifically for children.
Writers like Sir Walter Scott, Alexandre Dumas père, Jules Verne, Rudyard Kipling, and Robert Louis Stevenson expanded the boundaries of what could be considered an adventure tale. Their works laid the groundwork for contemporary standards while maintaining the core element of danger.
The standard plot structure involves a hero undergoing a first set of adventures before meeting his lady, followed by a separation period. The second set of adventures then leads to a final reunion between the separated lovers.