Often, the same game can be speedrun in many different ways each way is referred to as a category, and each category has its own set of rules and leaderboard.
In order to compete with other players' times, speedrunners come together to create leaderboards and agree upon a set of rules for what is allowed in the speedrun. Execution refers to how well a player is able to play the game and perform the necessary strategies. Strategies ("strats" for short) are techniques which have been developed to save time. Pulling off a successful speedrun requires a combination of good strategy and execution. As such, story and exploration take a back seat a speedrunner will skip everything they can, and will often perform actions that seem quite illogical and even impossible to a casual player. A speedrunner is not interested in the game's intended experience - they are instead focused on how they can optimize their gameplay to achieve the absolute fastest possible time.
Speedruns can be considered a form of Emergent Gameplay, as they look and feel very different to casual play. A speedrun is a playthrough of a game with the intent of completing it as fast as possible for the purposes of competition, entertainment, or as a Self-Imposed Challenge.