Web frontend
If you open up a web browser and point at the http interface port for istatd -- by default, port 8000 -- you will find the istatd webapp. This is the main method by which users will generally interact with the system.
On the left, you have a tree view of counters. Each period in a counter name generates a level in this tree. Clicking the name of a counter will add it to the currently selected graph in the bottom-right area. If no graph is currently selected, a new graph is created and the counter is added to that.
To filter the list of graphs, type in a wildcard expression (* = match any substring, ? = match any subfield) -- or just a subset of the name of a counter, such as idle -- and press return. The tree will be reduced to show only counters that contain this as part of its name.
At the top is a number of controls for the application. The Refresh button will refresh all the graphs, to make them up to date with the latest data. The auto-refresh button, when toggled on, will make the window update itself every so often -- by default, every 10 seconds, unless a larger time range is selected.
The time range bar lets you select how much data you want to see. From the last 5 minutes, to the last 5 years. The istatd server will give the most accurate data available for the time range, filtered down to the size of the window. This means that, when viewing very large time ranges, you may see averages and standard deviations of intervals larger than the sampling interval. This means that you can zoom in, by clicking and dragging horizontally in a graph window, to see better resolution. To zoom back out, click the zoom-out button in the graph window, or simply double-click. Note that all graphs zoom and scroll in parallel with the window you are investigating; this is to make investigation of particularly interesting points in time easier.
There are three standard chart sizes to choose from, or you can choose to type in your own size (as WxH -- for example, 1920x1080.)
Finally, there are some advanced features that let you search-and-replace across all graphs you're currently viewing, which is useful when you for example have a dashboard suited to investigating a particular host by name (found in the counter,) and then want to look at another host by name. Additionally, there is the option to completely customize your time range, to pick specific start and end time, and maximum number of samples.
The configuration of graphs, windows and options can be saved into a user-specific "dashboard." For more information, see Users and dashboards.