From Halopedia, the Halo wiki
"Spawn Points" redirects here, for Forge objects and Forging, see here.
In computer and video games, especially first-person shooters, spawning is the in-game creation of an entity, for instance a player character, non-player character (NPC), or an item. Respawning is the recreation of a player, NPC or monster after its death or destruction, or at the end of a round.
Spawning of players occurs at the beginning of the round and respawning occurs after being killed or destroyed, either immediately or after a delay. Players spawn at spawn points or spawn sites, usually scattered throughout the map. However, in levels designed for team play, there may simply be two areas, one for each team. Some players will lie in wait around spawn points to kill players as they spawn, a frowned upon practice known as spawn camping. Spawn points for in-game objects other than players are often used and abused in a similar fashion in other types of games, such as MMORPGs. Similarly, the word respawn can be used to describe an item or NPC that reappears in the same area after it has been picked up or killed (respectively). Certain design flaws in maps can be taken advantage of by players who wish to spam a spawn with explosives.
In Forge, one may place spawn points where they wish, in which the arrow faces the direction in which they will face spawning. They can be moved just like normal objects in Forge, and though appear tangible in Forge, they do not show up in the actual game. Just because a spawn point is placed does not mean they will always spawn there; some combinations of a map, a gametype, and a map's construction will cause players to spawn elsewhere (i.e. placing a box on all spawn points). In some objective games, there is a different spawn point for each team.