# Modeling Time

A transaction in a Balancer Pool is modeled as a discrete-time event updating the pool's state. They are referred to internally as Actions.

* similarly, price updates are processed as state updates
* the timestamp of every transaction, included in transaction data such as BigQuery Ethereum-Balancer, is preserved in the simulation output
* the simulation returns a datetime64 in 'change\_datetime'
* datetime allows to use any Python library for analysing and manipulating time series data