Description: The term ‘Append-only’ refers to a data structure that allows for the insertion of information without the possibility of deletion. This approach is fundamental in the design of systems that require an immutable record of events or data, where each entry is permanent and accumulates over time. Append-only data structures are particularly useful in contexts where data integrity is critical, such as in auditing systems, transaction logs, and real-time data analysis. By not allowing data deletion, it ensures that all historical information is available for analysis, facilitating traceability and transparency. Additionally, these structures are often simpler to implement and manage, as they eliminate the complexity associated with data deletion and modification. In programming and software development, append-only structures can be implemented through various forms such as lists, write-only databases, or event logging systems, where each new piece of data is added to the existing collection without altering previous data. This feature makes them a valuable tool for applications that require continuous tracking and thorough analysis of information over time.