# Class structure
All production classes are located in `src/`, and all unit and integration
tests are located in `tests/`.
## Core/
### Bootstrap
This class bootstraps the phpList core system.
## Domain/
### Model/
These classes are the domain models, which map to some of the database tables,
and where the model-related business logic can be found. There must be no
database access code in these classes.
### Repository/
These classes are reponsible for reading domain models from the database,
for writing them there, and for other database queries.
## Security
These classes deal with security-related concerns, e.g., password hashing.