Introduction to SensorThingsAPI data model
Here is a diagram showing the different classes from OGC SensorThings API Part 1: Sensing Version 1.1
For those who are familiar with ISO 19156 (aka OGC OMS), you will find those data models have a lot in common.
The main class to consider is the Observation that enables to declare the result that was obtained at a specific date, location, following a particular procedure. The ObservedProperty, Sensor, Thing and FeatureOfInterest enable to characterize those parameters.
The main difference with OMS rely in the fact that STA introduce the DataStream concept as a way to group observations that "come together".
This is very common with repeated measures like timeseries, or measurements made along a trajectory. The datastream enable to group those observations and avoid repeating parameters that remain unchanged like the Sensor or Observed Property.
Going further with a video: https://www.youtube.com/watch?v=bYDSgs2fKLk
Going further with the OGC Specs: https://docs.ogc.org/is/18-088/18-088.html
An extension of this data model is proposed to accomodate the provision of borehole data. See STA Borehole Model