Daytime is the least dangerous time of a Minecraft day, it lasts for about 10 minutes real-time and is the time of day which all players Spawn in newly created single player maps.
Effects on gameplay
During the daytime, the sun shines on the surface, providing an optimal view of the player's surroundings, allowing them to explore the environment with ease.
During the day, hostile Mobs will not spawn on the surface, though they will still spawn underground in places such as caves, or in some other dark places such as roofed forests. Zombies and Skeletons will burn in direct sunlight, but they can take shelter in the shade of a Tree, an overhanging structure or landmass, or in Water. Spiders are neutral during the day unless attacked, or encountered in darkness. Endermen typically do not spawn in the daytime and they will teleport back to The End at the beginning of the day. However, if an Enderman happens to still be around in the early morning, before it has teleported back to the End, it will avoid the player, even when looked at or attacked. Other hostile mobs, such as Creepers, will be unaffected by daylight, and just as dangerous as they are in the dark.
During the day, villagers will come out of their houses as soon as dawn has ended, and will remain outside for the remainder of the day until dusk. At dusk, villagers go back into their houses to wait out the night.
During the day, if it rains, the light level will be lowered significantly. Thunderstorms will lower light the most, allowing monsters to spawn even during the day. Rain also allows Zombies and Skeletons to survive the day without shade or water bodies.