HTTP/2 is an advanced protocol that offers improved performance, efficiency, and enhanced user experience, making it a valuable choice for optimizing web communication.

HTTP/2 is the second major version of the Hypertext Transfer Protocol (HTTP), a protocol governing the communication between web browsers and servers. It introduces several enhancements over its predecessor, HTTP/1.1, with the aim of improving web performance and efficiency.

These enhancements include multiplexing, a binary protocol, header compression, server push, prioritization, and stream dependencies. By enabling concurrent requests and responses, efficient data representation, reduced header overhead, proactive resource delivery, and optimized resource loading, HTTP/2 enhances web browsing by making it faster and more efficient.

The steps discussed below are a simplified explanation of how HTTP/2 works. The actual process involves more complicated steps. They can vary based on particular circumstances of the communication and the specific implementation of the protocol.

A client (like a web browser) starts a connection to a server using TCP (Transmission Control Protocol). If the client supports HTTP/2, it includes an "HTTP2-Settings" header field in the HTTP/1.1 request.

The server acknowledges the client's HTTP/1.1 request. If it also supports HTTP/2, it includes an "Upgrade: h2" header in its response.

After recognizing that both ends support HTTP/2, they agree to switch protocols. From this point onwards, the communication will happen using HTTP/2.

The client and server will now communicate in binary format. All communication is broken down into smaller messages and frames and then transferred over the established connection.

The client sends a request to the server in the form of binary frames. Each request is assigned a unique identifier (stream ID).

The server receives the request, processes it, and sends back the response, again in binary frames. The response is associated with the request via the unique stream ID.

Upon receiving the data, the client reassembles the binary frames into the complete message according to their stream IDs and then processes the responses.

The connection remains open for more requests and responses. This is in line with HTTP/2's philosophy of reusing connections instead of opening and closing for each request-response cycle.

Once the client-server communication is done and there are no more requests to handle, the connection can be closed.

The differences between HTTP/1.1 and HTTP/2 can be summarized as follows:

HTTP/1.1: It uses a text-based protocol where requests and responses are sent as plain text over the network.

HTTP/2: It uses a binary protocol where data is sent as a series of binary frames. The binary format allows for more efficient parsing and processing.

HTTP/1.1: It uses multiple TCP connections, resulting in a limitation known as "head-of-line blocking." This means that requests must wait for previous responses to be complete before being processed.

HTTP/2: It supports multiplexing, allowing multiple requests and responses to be sent and received concurrently over a single TCP connection. This eliminates head-of-line blocking and improves performance by reducing latency.

HTTP/1.1: Headers are sent as plain text in each request/response, resulting in redundant data transfer, especially for repetitive headers.

HTTP/2: It uses the HPACK compression algorithm to compress headers, reducing the overhead of header data and optimizing bandwidth usage.

HTTP/1.1: Servers can only respond to client requests. Additional resources need to be explicitly requested by the client.

HTTP/2: It introduces server push, where the server can proactively send additional resources to the client without waiting for explicit requests. This improves page load times by reducing the round trips needed to fetch dependent resources.

HTTP/1.1: Requests are processed in the order they are received, without explicit priorities assigned.

HTTP/2: It supports request prioritization, allowing clients and servers to assign priorities to different requests. This ensures that more important resources are delivered first, optimizing the order in which resources are loaded.

HTTP/1.1: It does not provide a mechanism for expressing dependencies between different resources.

HTTP/2: It introduces the concept of stream dependencies, where requests can depend on or be associated with other requests. This allows for more efficient resource loading and better handling of dependencies between resources.

Read: Redirecting HTTP to HTTPS: A Step-by-Step Guide

HTTP/2 offers several features that enhance performance. Multiplexing allows multiple requests to be sent concurrently over a single TCP connection, reducing latency and improving overall response times. This feature is particularly beneficial for websites with numerous resources, such as images, scripts, and stylesheets.

The binary protocol used in HTTP/2 reduces the time required for parsing and processing compared to the text-based protocol of HTTP/1.1. Additionally, header compression significantly reduces the overhead of header information, optimizing bandwidth usage and further reducing latency.

HTTP/2 facilitates the automatic delivery of resources by the server to the client, eliminating the need for explicit requests. This accelerates page loading and enhances the performance of web applications.

Delivery Order Optimization is a feature in HTTP/2 that enhances resource loading efficiency and prevents delays caused by lower-priority content. With HTTP/2, resources can be prioritized, allowing the server to determine their delivery order. This optimization minimizes the impact of lower-priority resources on the loading of higher-priority content, resulting in a smoother and faster browsing experience.

HTTP/2 is designed to be fully backward compatible with HTTP/1.1. It means that even if a client or server does not support HTTP/2, communication can still occur using HTTP/1.1. This compatibility allows the gradual adoption of HTTP/2 without requiring immediate infrastructure changes.

HTTP/2 introduces additional complexity compared to HTTP/1.1 due to its binary framing and multiplexing mechanisms. Implementing and maintaining HTTP/2 support may require more effort and expertise, especially for developers and system administrators.

While HTTP/2 offers improved performance, it can consume more server resources compared to HTTP/1.1. The need to maintain and manage a higher number of concurrent connections may increase server memory and CPU usage. However, efficient server configurations and optimizations can mitigate these concerns.

The improved performance of HTTP/2, with its multiplexing and server push features, can pose challenges for caching. Caching becomes more complex as individual resources are dependent on others and may change dynamically. Careful cache management and configuration are necessary to ensure the effective utilization of caching techniques with HTTP/2.

Despite these disadvantages, the overall advantages of HTTP/2 in terms of performance improvements, reduced latency, and enhanced user experience make it a compelling choice for modern web applications. The challenges associated with implementation and resource consumption can be addressed through proper planning, optimization, and ongoing maintenance.

HTTP/2 represents a notable advancement in Internet technology, offering enhanced performance, security, and resource management. As more browsers adopt HTTP/2, transitioning to this protocol is a wise decision for both developers and website administrators. The improvements introduced by HTTP/2 contribute to improved user experiences, which can positively impact engagement and conversion rates.