> ## Documentation Index > Fetch the complete documentation index at: https://docs.fyvel.io/llms.txt > Use this file to discover all available pages before exploring further. # Booking layers & snapshots > Use booking layers and snapshots deliberately in reporting Booking layers help you keep different data layers cleanly separate in reporting. Instead of mixing every value in a single layer, you choose exactly which booking layers a report should include. Booking layers in Fyvel with a table for import, manual bookings, personnel costs, custom layers, and snapshots ### What booking layers are for Booking layers are suited to, for example: * **imported accounting values** * **manual additions or corrections** * **forecast-like values** * **values from the personnel-cost logic** In the report you select exactly the layers that matter for your question. ### Upload values to booking layers Booking layers can also be filled through the Excel add-in and the Google Sheets add-in. That way you can write values from a spreadsheet model back into a specific booking layer in Fyvel, for example for planning, forecast, or modelled additions. The guide is under [Upload values to booking layers](/en/documentation/working-with-fyvel/upload-booking-layers). Add-in setup is on [Excel & Google add-ins](/en/documentation/working-with-fyvel/add-ins). ### Why this helps With booking layers you can: * keep actuals and internal additions separate * manage different planning views side by side * assemble reports flexibly for different audiences or occasions ### Snapshots A snapshot is a **locked booking layer** that freezes a specific set of figures. A snapshot does not store the underlying individual bookings. It stores the aggregated values at category and reporting-section level, including cost centers. That is especially useful when you want to: * keep the state when a plan is finalised * compare changes since an earlier cutoff date * document preliminary estimates Changes to category mappings or reporting sections do not apply retroactively to snapshots that already exist. Old snapshot data stays unchanged. After it is created, a snapshot can be selected in reports and in the add-ins like any other booking layer. *** This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.