What type of blobs can only have new blocks added to the end and not be updated?

Append Blobs are designed specifically for scenarios where you need to continuously add data without the ability to modify existing content. This is particularly useful for logging scenarios where new entries need to be appended continuously, but old records should remain unchanged. With Append Blobs, the architecture allows you to only add new blocks to the end of the blob, ensuring data integrity and consistency, as no updates or deletions can be made to the already stored data within the blob.

In contrast, Block Blobs can both append new blocks and replace existing blocks, which allows for more flexibility in instances where data needs to be updated frequently. Page Blobs, on the other hand, are optimized for random read and write operations, typically used for virtual hard disks where both modification and updating of data are often required. The term "Standard Blobs" does not refer to a type of blob within the Azure ecosystem but rather may confuse users about the specific characteristics of Azure blob storage types.

By focusing on the functionality of Append Blobs, you can appreciate why they are the best choice for applications needing an efficient way to capture a growing stream of data without modifying previous entries.