Glossary
Look up any term the site uses, with its source
A dotted line under a word on any page links it here. Each definition names where it comes from.
terms.json every term, its definition and its source
H100-equivalent appears in more sections than any other term
a filled square · the section links the term| Term | This week | Buildout | Power | Machine | Chips | Jobs | Ledger | Frontier | Records | Companies |
|---|---|---|---|---|---|---|---|---|---|---|
| AI exposure category | used in This week | used in Jobs | ||||||||
| AI supercomputer | used in This week | used in Buildout | used in Chips | used in Companies | ||||||
| Arena score | used in Frontier | |||||||||
| Average selling price | used in Chips | |||||||||
| Balancing authority | used in Buildout | used in Power | ||||||||
| Bit shipments | used in Chips | |||||||||
| Capacity price | used in Power | used in Chips | ||||||||
| Capacity utilization | used in Records | |||||||||
| Capital cost | used in Buildout | |||||||||
| Capital intensity | used in Chips | |||||||||
| Capital spending | used in This week | used in Buildout | used in Records | used in Companies | ||||||
| Chip plant | used in This week | used in Machine | used in Companies | |||||||
| Chiplet | used in Chips | |||||||||
| Cloud region | used in This week | used in Buildout | used in Companies | |||||||
| Defect density | used in Chips | |||||||||
| Delivery year | used in Power | |||||||||
| Diffusion index | used in Chips | |||||||||
| Entity List | used in Chips | |||||||||
| Facility power | used in Buildout | used in Power | used in Machine | |||||||
| Foreign direct product rule | used in Chips | |||||||||
| Framework | used in Power | used in Companies | ||||||||
| Gross margin | used in Chips | |||||||||
| H100-equivalent | used in This week | used in Buildout | used in Machine | used in Chips | used in Companies | |||||
| Herfindahl index | used in Chips | |||||||||
| High-bandwidth memory | used in Chips | |||||||||
| Home power price | used in This week | used in Power | used in Chips | used in Records | ||||||
| HS code | used in Machine | |||||||||
| Industrial price | used in Power | used in Chips | ||||||||
| Interposer | used in Chips | |||||||||
| Inventory days | used in Chips | |||||||||
| IT power | used in Buildout | |||||||||
| Job postings index | used in Jobs | |||||||||
| JOLTS | used in Jobs | |||||||||
| Large-load tariff | used in Power | |||||||||
| Life-cycle emissions | used in Power | |||||||||
| Load factor | used in Power | |||||||||
| NAICS | used in Machine | used in Records | ||||||||
| Nameplate capacity | used in Power | |||||||||
| Net import reliance | used in Chips | |||||||||
| New high, new low | used in This week | used in Power | used in Chips | used in Records | ||||||
| Open weights | used in This week | used in Frontier | ||||||||
| Producer price index | used in Machine | used in Records | ||||||||
| Recent graduates | used in Jobs | used in Records | ||||||||
| Reticle limit | used in Chips | |||||||||
| Saturation | used in Frontier | |||||||||
| Seasonally adjusted | used in Machine | used in Jobs | used in Records | |||||||
| Seasonally adjusted annual rate | used in Buildout | used in Chips | used in Records | |||||||
| SOC code | used in Jobs | |||||||||
| Under contract | used in Power | used in Companies | ||||||||
| Unit value | used in Chips | |||||||||
| Uprate | used in Power | |||||||||
| WARN notice | used in Ledger |
Buildout
Buildout →- H100-equivalent H100e
- A unit of computing power: the peak operations per second of a cluster divided by those of one Nvidia H100 chip. Epoch AI treats it as a rough guide to scale.
- IT power
- The power that the servers, storage and network equipment of a data center draw. Epoch AI estimates it from satellite imagery, permits and company statements.
- Facility power
- IT power plus the power for cooling and other overhead, which is what the whole site draws. The megawatts of a data center on this site are facility power.
- Capital cost
- Epoch AI’s estimate of what a data center costs to build and equip, in US dollars of 2025. Epoch models it from the site’s IT power with a cost per watt.
- AI supercomputer
- One cluster of AI chips on one campus, joined by a high-bandwidth network. Epoch AI stopped adding to its list of them, and the newest went into operation in July 2025.
- Cloud region
- A place where a public cloud provider runs data centers under one region name, as the provider’s own list gives it. A region is live once the provider lists it as open, and announced before that.
- Seasonally adjusted annual rate
- A month’s figure scaled to a full year and corrected for the season, so that any two months compare. The Census Bureau reports construction spending this way.
Power
Power →- Home power price
- What homes paid for each kWh in a month: the revenue that utilities report from residential customers, divided by the electricity they sold them. EIA publishes both each month for each state.
- Balancing authority
- The operator that keeps supply and demand matched on one part of the grid, such as PJM or ERCOT. EIA reports what each one generates by source every hour, and this site calls each one a grid.
- Nameplate capacity
- The most power a generator is rated to make, in megawatts. EIA lists every generator of 1 MW or more by it; what a plant makes over a year is less.
- Large-load tariff
- A utility’s terms for very large new loads such as data centers: the size that brings a load under them, the share of reserved power the customer pays for whether used or not, the shortest contract, and any exit fee or collateral.
- Capacity price
- What PJM pays power plants and other resources to be available in a future year, set by its base residual auction, in dollars per megawatt-day. Utilities in PJM pass the cost on to customers’ bills.
- Delivery year
- The twelve months from June to May that one PJM capacity auction buys for, written as 2024/25.
- Industrial price
- What industrial customers paid for each kWh: the revenue that utilities report from them, divided by the electricity they sold them. It is an average over every such customer, not a tariff.
- Load factor
- A load’s average power over a period divided by its peak power in that period. A data center that draws its full power every hour of a year has the highest load factor there is.
- Life-cycle emissions
- The greenhouse gases from building, fuelling and running a power source over its whole life, in grams of CO2-equivalent for each kWh it generates. Ember gives one factor for each source.
- Under contract
- A nuclear agreement that its own release calls a power purchase agreement, an energy purchase agreement or an offtake.
- Framework
- Any other nuclear agreement: a development agreement, an option, a memorandum, a target or a plan that waits for a regulator.
- Uprate
- More output from a reactor that is already running, after its owner upgrades it.
Machine
Machine →- Chip plant
- A semiconductor fabrication plant, as Wikipedia’s list of them gives it. The list says it is incomplete, so this site maps and counts the plants and compares nothing else.
- HS code
- A product code from the Harmonized System, the classification most countries use for trade. This site uses six-digit codes, such as 847150 for servers.
- Producer price index PPI
- A BLS index of the prices that US makers receive for what they sell, by industry and by month.
- Capacity utilization
- An industry’s output as a percent of its capacity, from the Federal Reserve’s G.17 release. This site follows it for makers of chips and other electronic components.
- NAICS
- The North American Industry Classification System, the list of industry codes that the US, Canada and Mexico share. Code 3344 is semiconductors and other electronic components.
Chips
Chips →- Reticle limit
- The largest area one exposure of a lithography scanner prints, 26 by 33 mm. One die cannot be larger, so the largest chips join several dies.
- Defect density
- The number of killing defects a process leaves per square centimetre of wafer. The larger a die, the likelier it is to catch one, so fewer large dies work.
- Chiplet
- One of several smaller dies, each tested before assembly, that are joined in one package to work as one chip.
- Interposer
- The slab of silicon under a chip’s dies and its memory that wires them together. It is made on wafers of its own, with a coarser process than the dies.
- High-bandwidth memory HBM
- DRAM dies stacked on top of each other and set beside a chip on its interposer. NVIDIA’s H100 carries 5 stacks.
- Herfindahl index HHI
- How concentrated production is: the sum of each producer’s squared percent share. One producer scores 10,000; many small ones score near 0.
- Net import reliance
- Imports minus exports, adjusted for changes in stocks, as a percent of what the US uses. USGS publishes it for each mineral.
- Capital intensity
- Capital spending over revenue: the share of what a company sells that it puts back into plants and tools. A chip maker runs far higher than a chip designer.
- Inventory days
- Stock at a year’s end over the year’s cost of revenue, times 365: how many days of sales a company holds. A rise can mean demand fell short of output.
- Entity List
- The US list of parties abroad that need a licence to receive items subject to the Export Administration Regulations. The Bureau of Industry and Security keeps it.
- Foreign direct product rule
- A rule that extends US export controls to items made abroad with US technology. Some Entity List entries carry it, which reaches chips and chip tools made outside the US.
- Gross margin
- Revenue less the cost of making what was sold, as a share of revenue. For a memory maker it rises and falls with memory prices.
- Diffusion index
- The share of a set of measures that are improving at one time. It shows how broad a turn is, not how large.
- Unit value
- The value of a trade flow over its quantity. On the memory desk it is what the EU’s importers paid for one chip: the value they declared over the count of pieces.
- Average selling price ASP
- What a company received, on average, for each unit it sold. Micron gives the change in it for DRAM and NAND each quarter, beside the change in bits shipped.
- Bit shipments
- The memory a maker shipped, counted in bits rather than in chips, so that a denser chip counts for more.
Jobs
Jobs →- AI exposure category
- The group, from Low to Very high, that BLS gives an occupation by how much of its work AI could do or already does, ranked against other occupations. BLS says that exposure does not imply job loss.
- SOC code
- A code from the Standard Occupational Classification, the US government’s list of occupations, such as 31-1120 for home health and personal care aides.
- Seasonally adjusted
- Corrected for the usual pattern of the calendar, such as extra hiring before the holidays, so that a change from one month to the next shows a real move.
- JOLTS
- The Job Openings and Labor Turnover Survey: the BLS monthly count of job openings, hires and separations.
- Recent graduates
- People aged 22 to 27 with a bachelor’s degree or higher, as the Federal Reserve Bank of New York defines them.
- Job postings index
- Indeed’s count of the job postings on its site, seasonally adjusted, as a seven-day average indexed to 100 on 1 February 2020.
Ledger
Ledger →- WARN notice
- A notice that an employer must file before a plant closing or mass layoff, under the Worker Adjustment and Retraining Notification Act. Since March 2025 the New York form asks whether AI or automation is a reason.
Frontier
Frontier →- Arena score
- A rating fitted with the Bradley-Terry model to people’s votes between two anonymous models. Two scores whose 95% confidence bounds overlap do not show a clear lead.
- Open weights
- A model whose trained weights its maker publishes for anyone to download and run. This site follows the licence that Arena lists for each model, and calls the others proprietary.
- Saturation
- A benchmark is saturated on the day a model first scores 90% on it. The saturation clock counts the days from the benchmark’s release to that day, from Epoch AI’s own runs.
Records
Records →- New high, new low
- The newest reading of a series when it is above, or below, every earlier reading this site holds for it. The history starts where the site’s copy starts, and each statement names that start.
Companies
Companies →- Capital spending capex
- What a company paid in a quarter for property and equipment, as the investing part of its cash-flow statement reports it. Each company names the line in its own way.