Adventure Mode

As said in Minecraft Wiki
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Adventure mode is a game mode intended for adventuring in which the player cannot place or destroy blocks, so as to avoid spoiling adventure maps by changing the map. The player can still interact with blocks that can be toggled, such as doors, levers, and buttons. The player can also still deal damage to mobs and trade with villagers.
It is likely that one would import and use custom adventure maps to be played, as a new map would not have much purpose or customizability, and a custom map would control certain aspects of the gameplay as well.
In Adventure mode, the player cannot simply get resources by breaking items or by destroying or building blocks. The only way the player can get certain resources is by killing mobs, looting chests or trading with villagers. However, depending on what type of an adventure it may be, many of these features are unnecessary, or often unavailable by conventional means. It may also be a way to cheat on a map that restricts the acquisition of specific objects.
Although it is impossible to destroy blocks manually, it remains possible to use an explosion to get some resources. However, this may ruin the aspect of gameplay by acting as a way to cheat a map, as well as an annoyance from Creepers, and is controllable using the mobGriefing server command. Explosions can also damage a map, rendering it unplayable or ruined.
While it is possible to play a normal Minecraft game in Adventure mode, it is quite difficult to do so. Most time is spent collecting food to replenish the ever-dwindling food bar. It is possible to collect some trade goods such as wool, raw porkchops, and wheat (by jumping on the wheat found in villages), as well as finding chests in blacksmiths, dungeons, abandoned mineshafts, and strongholds. Wood can only be obtained by using a Creeper near log structures and trees."