Analyst: Someone performing analysis.
This is more general than data scientist.
Ping: A message sent to our telemetry servers. Most commonly, a ping comes from Firefox and contains information on browser state, user actions, etc.
(more details), but can also come from other Mozilla products or services
Dataset: A set of data, includes ping data, derived datasets, etc. Can also refer more specifically to a BigQuery dataset which is a container for tables.
Derived Dataset: A processed dataset, such as main_summary or the
Session: The time from when a Firefox browser starts until it shuts down
Subsession: Sessions are split into subsessions when a 24 hour threshold is crossed or an environment change occurs