The buildings in each Dota 2 base that periodically spawn lane creeps are the Barracks. Each base has melee and ranged Barracks, which produce the units that march along the three lanes toward the enemy base.
Barracks are also important defensive objectives. Destroying an enemy melee or ranged Barracks does not end the match, but it weakens that lane by preventing the corresponding type of creep from spawning normally. This gives the opposing team a lane advantage and makes its remaining structures easier to pressure.
A common mix-up is confusing Barracks with Towers. Towers defend lanes and attack nearby enemies, while Barracks are production structures. Fountains heal and replenish heroes near the base, and Outposts are map-control structures rather than creep-production buildings.
Barracks are located behind the base's defensive towers, near the Ancient. Teams often prioritize them when attacking because removing both Barracks makes the enemy's lane creeps significantly less threatening.