# Time dimension (/docs/indicator-apps/dimensions/time)



Every indicator in an indicator app is tracked over time, one value per **period**.
The **time dimension** is what makes an indicator app a record of how a metric
moves rather than a single snapshot. Before you collect any values, you choose how
often each indicator is measured.

## Choose the collection interval [#choose-the-collection-interval]

The **collection interval** (also called the period type) is how often an indicator
gets a value. You pick one of five: **Daily**, **Weekly**, **Monthly**,
**Quarterly**, or **Yearly**.

Choose the interval that matches how the real-world measurement happens. A meter you
read monthly should be a monthly indicator; an annual target should be yearly.

## How periods work [#how-periods-work]

Once an indicator has an interval, you collect and see its values period by period.
You move between periods to enter a value for each one, for example typing in
January's figure, then February's, and so on. When you look at the data, you see the
value laid out across the periods, so the trend over time is easy to follow. You can
move forward and back through the periods, and focus on a particular range of them.

## How time grains relate [#how-time-grains-relate]

Indicators that are measured at different intervals can still relate to each other.
A finer interval can roll up into a coarser one: twelve monthly values add up to a
yearly total, for example. Ovidens understands these relationships, so a yearly
metric can be computed from monthly data without you doing the arithmetic by hand.
You will see this in action when you build a
[calculation](../indicators/formula.mdx) that combines indicators tracked at different
intervals.