Technological Achievement Tiers

The Forerunner categorized the Techonlogical Advancement of civilivations into tiers.

Tier 0: Transsentient
As the Forerunners had no examples of civilizations with technological accomplishment greater than themselves - with the exception of the Precursors - this is a theoretical ceiling. They can travel intergalactically and accelerate evolution of intelligent life. These may be creatures of legend.

Tier 1: World Builders
Forerunner ability to manipulate gravitational forces, create AI with full sentience, fabricate super-dense materials, and perform ultra-accurate slipspace navigation is unequaled by any extant civilization.

Tier 2: Interstellar
The Covenant's accurate slipspace navigation, near-instantaneous communication, and man-portable application of energy manipulation owes itself to Forerunner technology.

note: The two primary extant interstellar civilizations were space-faring prior to discovering Forerunner artifacts - or each other - but they have not successfully reverse-engineered those artifacts.

Tier 3: Space-Faring
Humans have efficient slipspace navigation, mass drivers, asynchronous linear-induction weapons, holocrystal storage, and semi-sentient AI, but their creation requires blood sacrifice, memory transfer, and flash cloning. They have had no outside influence - until recent events. Since Covenant contact, they have been on the verge of huge artificial advancement.

Tier 4: Space Age
Tier 4 is often the final resting place for species intelligent enough to break free from their cradle's surface only to fill the gulf surrounding it with war. Their comfort-focused technology can include medical advances.

note: Jiralhanae are the only species on record who achieved space, reduced themselves through internecine war to a preindustrial condition, clawed their way back to their former state, and learned nothing from the experience.

Tier 5: Atomic Age
Tier 5 species usually become space-farers, focusing on clean energy production. The occasional belligerent species will use atomic energy for weapons, often resulting in extinction. In-atmosphere craft are a hallmark, often leading to spaceflight.

Tier 6: Industrial Age
Tier 6 is often the pinnacle for a civilization. Agrarian societies can remain stable in the preindustrial stage, but Tier 6 population strain and mechanized food production invariably create political and economic pressures few can balance. Moving past this usually promises advancement. Some societies improve environmental and medical understanding concurrently with mechanical and transport advancement; those that do not are frequently doomed.

Tier 7: Preindustrial
Tier 7 is one of the most common and stable states, with limited weaponry and environmental threats. Societies tend to be small and scattered, driven by subsistence farming, foraging, or hunter-gathering needs. Technology is limited to simple tools, weapons, or agrarian implements and methods, but a basic understanding of planetary and solar mechanics is not uncommon.