A base is one of two (the other being the strike force) basic tools the commander has at their disposal in the Global Conquest mode of Kane's Wrath. They are represented on the main map by a circle with the faction's construction yard in the middle.
Bases are nerve centers in the quest for global domination. They provide ground control, support powers and a steady source of income. Income is determined by proximity to high Tiberium concentrations and cities. The more populated the city and the more Tiberium in the area, the more income will it generate per turn.
Initially, each commander has four tier 1 bases scattered across the map. New ones can be constructed by strike forces for 6000 credits (8000 for Scrin). If a strike force is composed of only the MCV (whether it was created as such, or the rest of it was destroyed by the enemy) it will be removed from play.
A useful tactic for Nod is to create a custom strike force consiting of only a MCV and a single additional unit. When establishing a base with this custom strike force, immediately follow up with the Guerilla Repairs power on the next turn. This allows the same cheap (and possibly Tier 1) strike force to establish several bases, without constantly building new strike forces from scratch for each base.