What is Cloud Storage?
Cloud Storage is Firebase's service for storing files that users upload. It can hold profile avatars, product images, PDFs, audio, video, receipt images, and more. Firestore is great for text/data, and Storage is great for files.
Using Firestore and Storage together
Upload the image file to Storage, then save the resulting download URL or file path in a Firestore document. For example, you could add an avatarUrl field to a user profile document.
Watch out for
If you don't validate upload file size, file type, and access permissions, storage costs can climb and unwanted files can sneak in. You need both client-side validation and Security Rules.