# Data sources

A data source is the starting point of every data pipeline in OVITO, providing the input data that flows through the pipeline and is processed by the modifiers. The active data source is displayed under the Data source section in the pipeline editor, as shown in the screenshot.

Data source type | Description
--- | ---
External file | Loads simulation data from external files (stored locally or remotely).
Python script pro | Executes a custom Python script to generate data dynamically.
LAMMPS script pro | Runs a LAMMPS simulation script within OVITO and forwards the output to the pipeline.

Additionally, the Python API provides the `StaticSource` class, which allows passing in-memory datasets to a pipeline.