Glossary

The words that Activity Monitor X uses, each with one meaning.

Processes and apps

Process: One running instance of a program, known by its PID and its start time together.
Program: The path of the executable that a process runs.
App: What the tables and charts show: the responsible app of a process, or the process itself when it has none.
Responsible app: The app that macOS holds responsible for a process, for example the app that started a helper process. A terminal app is never a responsible app.
Terminal app: An app whose child processes keep their own identity. By default: Terminal, iTerm, Ghostty and rootshell. Settings > Recording lists them.
Quiet system process: A process under /System, /usr (not /usr/local), /bin or /sbin whose average for the metric is very small. It is hidden by default and counts in Other.
Group: A set of apps that you make, chosen by rules (all, any, not) on the name, bundle ID, path or team ID.
Pinned app: An app that you put in the sidebar, with its own chart and processes.

Sample: One set of values for a process or for the Mac, at one time.
Tier: One step of the stored history: raw (5 seconds), minute or hour.
Range: The time that you look at: Live (the last 5 minutes, updated each second), 1H, 24H, 7D, 30D or 90D.
Span: A part of the range that you select on the chart.
Metric: What a chart or table shows: CPU, Memory, Disk, Energy, Network or GPU, and Score for groups.
Usual: The typical value of an app for the time shown, as an hourly mean, beside its average.
Other: The sum of all apps that do not have their own colour in the chart.
Top during peaks: The five apps that add most to the busiest times of the chart. They get their own colours.
Period: What the Calendar shows at one time: a day or a week of hours, or a month of days.

Event: A recorded moment: a step in memory pressure, a change of thermal state, or an alert.
Rule: One alert condition, with its threshold, the time that the value must stay past it, and the time before it alerts again.
Alert: An event that a rule writes when a value passes its threshold.
Severity: Info, warning or critical. Only warning (yellow) and critical (red) have a colour.
Preset: A set of rule values that AMX calculates for your Mac: Relaxed, Balanced or Strict. Custom, after you edit a value.
System CPU rule: The rule on the CPU of all cores: warning at 70%, critical at 90%, for 5 minutes by default. It also sets the colour of CPU in the Calendar and the menu bar.

Inspector: The pane at the right that shows the details of what you selected. With nothing selected, it shows a summary.
Event lane: The strip above the chart with marks for pressure (▲), thermal (◆) and alert (●) events.
Range bar: The bar above the chart with the ranges (1H to 90D) and Custom.
Footer: The strip at the bottom of the screen with the trend and the system numbers of the metric.
Preview card: The card that shows when you hover a chart, a cell or an item.
Menu bar item: CPU over memory pressure as two small numbers in the menu bar, with a dot for an unread alert.
Energy flow: The Energy diagram: watts from the power adapter and the battery into the Mac, then to the top apps and Other.

Activity: The Disk pane with the read and write charts, the disks and the volumes.
Space: The Disk pane that scans a volume or folder and shows what uses its space, as a map and a table.
Inventory: The Hardware table of what the Mac has and what is connected to it.
Chip: The Hardware drawing of the chip of the Mac: its CPU cores, its GPU and its memory, each filled to its use.