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Hydrogen 2.0 is out now. These archival Hydrogen 1.0 docs are provided only to assist developers during their upgrade process. Please migrate as soon as possible.

A session is a set of user interactions that take place within a given timeframe. Each session tracks the global data that's unique to each user.

The Hydrogen framework includes built-in support for session management. This guide provides an introduction to how sessions work in your Hydrogen app.

For example, session data might contain the products within a cart, site preferences, and user identity. Session data persists across page refreshes, but it eventually expires, depending on how it's configured.

Types of session storage

The following table describes the types of session storage available by default in Hydrogen:

Cookie session storageCookieSessionStorageThe default session storage mechanism for Hydrogen. Cookies are convenient because you don't need a database or another backend service to persist the data.
In-memory session storageMemorySessionStorageStores the session data within Hydrogen runtime memory. You still need to configure cookies because a unique session ID is stored within the browser cookie, even though associated session data is stored in memory.
File session storageFileSessionStoragePersists session data to the file system. This is useful if you need to store a lot of data in the session (more than the 4kb cookie limit/) and also have the data persist when Hydrogen restarts.
Cookie configuration is still necessary because a unique session ID is stored within the browser cookie, although associated session data is stored in the file system.

Configuring sessions

The Demo Store template comes pre-configured with session support.

By default, session data is persisted within a cookie. You can adjust the session cookie configuration within your Hydrogen configuration file for an in-memory storage or file-based storage (NodeJS only), or build your own storage adapter. Learn how.

Next steps