An Item spawn is an exact location at which a specific item appears at regular intervals, free for any player to take. Although many item spawns are almost useless, some can be quite valuable. Secondary Herblore ingredients are often item spawns, such as snape grass or red spiders' eggs.
The rate at which an item reappears is dependent on the item. Some items are very fast to spawn, such as white berries, but others, like guam leaves and the sapphire spawn in level 46 Wilderness are very slow.