Glossary: what the terms mean

What it meansThe connection between Home Assistant and a device, a service or a platform.

In plain wordsLike an app on your phone — except it connects the house rather than serving a screen.

In my houseThere are two paths to tado. The built-in dialog leads into the cloud; the local one is called something else and has to be started by hand. Read the whole story

What it meansThe physical thing an integration brings into the system.

In plain wordsWhat you can pick up. A device is rarely what you work with — entities are.

In my houseTwelve thermostats and one bridge became 13 devices — and 61 entities. Read the whole story

What it meansThe smallest thing in the system that has a state. One device usually brings several.

In plain wordsTemperature, humidity, battery — every property of a device is its own entity. You automate with these, not with the device.

In my houseAmong the 61 entities of the heating system there was not a single battery sensor. On this path tado does not publish the level. Read the whole story

What it meansAn entity’s technical name, such as sensor.kitchen_temperature. Not the same as the display name.

In plain wordsThe display name is for people, the ID is for automations. Renaming sometimes changes both — and you do not notice.

In my houseAn umlaut in the name changed the ID. The frost alarm then pointed at an entity that no longer existed — with no error message. Read the whole story

What it meansThe room or place a device is assigned to.

In plain wordsLets you say "all lights in the living room" without listing each one.

In my houseHome Assistant likes to put the area in front of the name when creating an entity. A door contact ends up with the hallway in its name twice. Read the whole story

What it meansThe interface where entities are shown and switched.

In plain wordsWhat the family sees. And the place where faults turn up that nobody else notices.

In my houseWhile building a dashboard it emerged that every entity of the UPS had read "unavailable" for 43 hours. Read the whole story

What it meansA rule that runs by itself: when this happens, check that, then do this.

In plain wordsTrigger, condition, action — in that order. Only the trigger is mandatory.

In my houseThe washing machine’s done-message triggers on the machine state, not on the error code — that reads unknown after a restart. Read the whole story

What it meansThe event that starts an automation. Without a trigger, nothing happens.

In plain wordsA time, a state change, a button press, a calendar entry.

In my houseAll-day events technically begin at 00:00. Pre-heating therefore triggers eight hours earlier — which lands inside the building’s heating window. Read the whole story

What it meansA check between trigger and action. If it does not hold, everything stops.

In plain wordsThe most common place for silent faults: a condition that never holds does not report. It just stays quiet.

In my houseA watchdog waited for a state that did not exist in that form. Ten hours without water, and not a single alert. Read the whole story

What it meansWhat happens once trigger and condition have passed.

In plain wordsCareful: an action reports that it was sent — not that it took effect.

In my houseThe switch says "requested", not "on". With the stove there was a measurable difference between the two. Read the whole story

What it meansA sequence of actions with no trigger of its own. Called from elsewhere.

In plain wordsThe best lever against sprawl: what twenty places need is written once, in the script.

In my houseEvery alert goes through a single script. When a second channel was added, not one caller had to be changed. Read the whole story

What it meansA stored state of several devices, applied all at once.

In plain wordsGood for "this is how it should be now". Bad when the state should depend on weather or time — use a script then.

In my houseFour buttons cover six heating zones, and the fireplace counts too. Read the whole story

What it meansWhat happens when an automation is triggered again while still running.

In plain wordssingle discards the second run, restart starts over, queued lines them up. The default is single — which explains most "why did it only react once" questions.

What it meansA ready-made automation to fill in: you only pick the devices.

In plain wordsA good start and a poor permanent solution. The moment you need an exception it does not foresee, you start over.

What it meansThe current value of an entity: a number, a text, on or off.

In plain wordson does not mean the same everywhere. On a door contact it means open.

In my houseIf the name does not convey that, you build the condition backwards — which is exactly why the names were reworked. Read the whole story

What it meansExtra information attached to an entity besides its state.

In plain wordsHandy for keeping related things together. Awkward because attributes do not reach long-term statistics.

In my houseAttributes have to be strings. A numeric value was silently dropped — the check passed, the attribute was simply missing. Read the whole story

What it meansTwo different kinds of "no number": unavailable means the entity does not answer. unknown means it answers but does not know the value.

In plain wordsNeither is a zero. Treat them like zero and you get averages nobody ever measured.

In my houseWithout a battery sensor, unavailable is the only warning. A radiator head then fails with no notice — in the middle of the heating season. Read the whole story

What it meansA small computation in the middle of text, in double curly braces.

In plain wordsPowerful and quiet. A template that finds nothing does not write "error" — it writes something.

In my houseAfter a reload the query briefly returned nothing. The template then wrote the word "None" as text into the measurement table — and the evaluation made a radio cell of its own out of it. Read the whole story

What it meansVirtual entities you create yourself: switches, counters, texts, times, schedules.

In plain wordsYour system’s memory. Without helpers an automation cannot know what happened yesterday.

In my houseA text helper recorded the antenna orientation — and was overwritten at every restart, because for input fields the initial value does not only apply at creation. Read the whole story

What it meansThe operating system for your own hardware, and the management layer above it that handles add-ons and backups.

In plain wordsThe most convenient way to run it. Without it there are no add-ons and no one-click backup.

In my houseThe Supervisor reported unknown_error whenever its answer was not JSON. The message described the tool, not the fault. Read the whole story

What it meansA separate extra program running alongside Home Assistant on the same machine.

In plain wordsNot to be confused with an integration. An integration connects; an add-on brings its own software.

In my houseThe regulator’s measuring client runs as a home-built add-on on bare Alpine — including a source patch that aborts if it does not match exactly. Read the whole story

What it meansThe community store for integrations and interface cards that do not ship with Home Assistant.

In plain wordsConvenient, but not a vetting body. What is there is not reviewed, only published.

In my houseIt is built in by now — and that made everything I had installed by hand invisible. Read the whole story

What it meansThe part that writes every state change into a database. By default for ten days.

In plain wordsYour memory for troubleshooting. One query over thirty days is worth more than thirty looks at the present state.

In my houseSix weeks of watching two thermostats, four interpretations, all wrong. The answer had been in the database all along. Read the whole story

What it meansCondensed hourly and daily values that remain long after the recorder has deleted the individual readings.

In plain wordsEverything about consumption and cost depends on it. Once lost, it cannot be restored.

In my houseTwo lost sets of long-term statistics and four corrupted database files before it was clear the memory card was to blame. Read the whole story

What it meansA motorised head that replaces the manual knob on a radiator and pushes the same valve pin.

In plain wordsIt controls the flow, not the heat. If the flow is cold, a fully open valve does not help either.

In my houseThe same head reports two temperatures: room sensor 27.6 °C, valve sensor 34.9 °C — and the one on the radiator is what gets shown. Read the whole story

What it meansThe one-off run in which a head finds and memorises the stops of the valve pin.

In plain wordsWithout it the head regulates blind. And a head that travels a little and then stops looks from the outside like one that works.

In my houseThree heads aborted at 1,071, 1,143 and 1,187 steps. Three independent defects do not produce an identical number — so it was the mechanics. Read the whole story

What it meansAn input through which you feed the head the temperature from another sensor.

In plain wordsThe single most important feature on a thermostat. It repairs the design flaw that its own sensor sits at the hottest point in the room.

In my houseOf three homes only one offers this input — and that is exactly where the control matches what you feel in the room. Read the whole story

What it meansA radio standard for sensors and switches. Mains-powered devices relay for the battery-powered ones.

In plain wordsNeeds a stick on the machine, but no Wi-Fi password per device. More devices make the network better, not worse.

In my houseSix valves moved from Bluetooth to Zigbee — and the mesh measurably improved in the process. Read the whole story

What it meansApple’s home standard. Many devices speak it locally, even with no Apple device in the house.

In plain wordsThe key catch: a HomeKit accessory only ever allows one controller. Pairing it takes it away from the other one.

In my houseOnly after the home was deleted in Apple Home did the status field flip and the pairing succeed on the first try. Read the whole story

What it meansMatter is the common language of several manufacturers, Thread the low-power radio beneath it.

In plain wordsThe decisive difference to HomeKit: Matter explicitly provides for several controllers at the same time.

In my houseMatter would have been the better path here. But the bridge did not advertise it in its announcements — whether it could do it in principle remains unsettled. Read the whole story

What it meansWhether a command stays inside the house or travels via somebody else’s server first.

In plain wordsThis is not only about privacy. It is the question of whether your house still works when the internet is down or a company shuts the service.

In my houseFor thirteen hours the water shut-off hung on the cloud, because an address in the house had been reassigned. Read the whole story