# Sequencing Layer The sequencing layer is a pivotal component in rollup systems, primarily responsible for receiving user transactions, sequencing the transactions and bundling them into batches. These batches are then committed to the settlement layer. Additionally, in scenarios where the system employs an external DA layer, the sequencer also ensures efficient transmission of transaction data to the DA layer. Similar to other rollups, App Rollups will start with a centralized sequencer model. While this approach offered certain development efficiencies, it also presents challenges and risks, such as potential single point of failure, transaction censorship and issues around miner extractable value (MEV), affecting network fairness and transparency. To address these concerns, zkLink X aims to incorporate decentralized sequencer solutions. These solutions, including platforms like Espresso, Astria, and Fairblock, aim to mitigate centralization risks by processing and validating transactions across a distributed node network. This strategy will not only boost network security and transparency but also strive to offer a more secure, equitable, and efficient rollup solution to its users. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.zk.link/architecture/sequencing-layer.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.