> For the complete documentation index, see [llms.txt](https://docs.reorc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.reorc.com/data-modeling/sources.md).
# Sources
A source is a reference to raw tables from database that you can use in your models.
In traditional SQL transformation, raw tables are typically referenced directly by their names. This leads to a few challenges, such as code readability and dependency management between tables. In contrast, sources introduce a more structured and modular way to reference raw tables, providing several benefits:
* **Clear data lineage**: Sources help you explicitly identify raw tables as external data sources. This helps establish clear data lineage, making it easier to trace data from raw tables to the transformed models.
* **Data testing**: Declaring raw tables as sources allows you to implement data tests. You can validate assumptions about the data quality, ensuring transformations applied later are based on trusted data.
* **Improved communication**: In source metadata, you can add descriptions, owners, and other information to clearly express your use cases. This creates transparency and improves communication across teams.
## Create a source
To create a source, follow these steps:
1. In the **Models** tab, click on the **+** icon and select **Add source**.
2. In the opened modal:
1. Select the connection type. Currently, ReOrc supports referencing from a warehouse.
2. Select the target connection. If you haven't set up the project connection, refer to: [Project connections](/connections/project-connections.md).
3. Click **Next**. ReOrc then displays all the tables available from the target connection.
Select tables from a connection
4. Select the desired raw tables or models.
5. Click **Add source**.
The selected tables will then be added to the **sources** folder and grouped by connection name.
You can view the schema of a source by opening it in the editor. A schema contains field name (or column name), data type, and comment.
## Select from a source
With raw tables organized by sources, you can reference them in a model using the `{{ source() }}` Jinja function. For more details, see: [Models](/data-modeling/models.md).
The function requires two arguments:
* `source_name`: the folder name that contains the source.
* `table_name`: the name of the table.
For example, with the `raw_orders` table added under the `jaffle_shop` folder, we can reference it as follows:
```sql
select
id as order_id,
customer as customer_id,
ordered_at as order_date
from {{ source("jaffle_shop", "raw_orders") }}
```
The above model is then compiled to:
```sql
SELECT
id AS order_id,
customer AS customer_id,
ordered_at AS order_date
FROM
`jaffle_shop`.`raw_orders`
```
