# 4 New trigger

#### Overview

In this section you will learn how to set up a trigger.

Items only collect data. To automatically evaluate incoming data we need
to define triggers. A trigger contains an expression that defines a
threshold of what is an acceptable level for the data.

If that level is surpassed by the incoming data, a trigger will "fire"
or go into a 'Problem' state - letting us know that something has
happened that may require attention. If the level is acceptable again,
trigger returns to an 'Ok' state.

#### Adding trigger

To configure a trigger for our item, go to *Configuration → Hosts*, find
'New host' and click on *Triggers* next to it and then on *Create
trigger*. This presents us with a trigger definition form.

![](../../../assets/en/manual/quickstart/new_trigger.png)

For our trigger, the essential information to enter here is:

*Name*

-   Enter *CPU load too high on 'New host' for 3 minutes* as the value.
    This will be the trigger name displayed in lists and elsewhere.

*Expression*

-   Enter: {New host:system.cpu.load.avg(180)}>2

This is the trigger expression. Make sure that the expression is entered
right, down to the last symbol. The item key here (system.cpu.load) is
used to refer to the item. This particular expression basically says
that the problem threshold is exceeded when the CPU load average value
for 3 minutes is over 2. You can learn more about the [syntax of trigger
expressions](/manual/config/triggers/expression).

When done, click *Add*. The new trigger should appear in the trigger
list.

#### Displaying trigger status

With a trigger defined, you might be interested to see its status.

For that, go to *Monitoring → Triggers*. After 3 minutes or so (we asked
to evaluate a 3-minute average after all) your trigger should appear
there, presumably with a green 'OK' flashing in the 'Status' column.

![](../../../assets/en/manual/quickstart/trigger_status.png){width="600"}

The flashing indicates a recent change of trigger status, one that has
taken place in the last 30 minutes.

If a red 'PROBLEM' is flashing there, then obviously the CPU load has
exceeded the threshold level you defined in the trigger.