For production applications, always combine this feature with external storage (cloud or database) and consider asynchronous downloads to keep your bot responsive.
Here is a complete guide on how to handle file downloads. telegram bot file download
Every file sent to a bot is assigned a unique identifier called a file_id . This string is included in the update object the bot receives (e.g., inside message.document.file_id for a document). The file_id is consistent for the same file in the same bot context, allowing you to reference it later. For production applications
When a user sends a photo, the API returns a photo array containing 3-4 versions (Thumbnail, Medium, Large). telegram bot file download