Message topics are a concept in message processing that allows messages to be categorized into topics or subjects and sent to various recipients interested in a specific topic.

In the context of message brokers or messaging services, topics enable the publication of messages related to a particular theme or category. These messages can then be received by multiple subscribers or recipients interested in that topic by subscribing to it.

A publisher, responsible for generating messages, sends a message to a specific topic, and multiple subscribers can receive these messages by subscribing to or registering interest in that topic. This topic-based communication allows for flexible, scalable, and targeted message distribution in distributed systems or applications.

For instance, a message topic could be 'Technology,' and all messages associated with this topic would be sent to subscribers interested in technology, while other subscribers interested in topics like 'Sports' or 'Science' would only receive messages related to those specific themes.

A queue is a data structure that operates on the principle of 'First In, First Out' (FIFO). This means that the first element inserted into the queue is the first one to be removed.

Think of it like a real-life queue: those who arrive first are also served first. In computer science and message processing, a queue is used to store elements or messages waiting to be processed by a process, application, or system.

For instance, a message queue in a message broker works similarly. When an application sends a message, it's placed in the queue, waiting there until it's picked up and processed by another application or system. This facilitates efficient, ordered, and timed processing of messages or tasks.

A Message Broker is a software component that facilitates communication between different applications or systems by receiving, forwarding, and delivering messages. It acts as an intermediary, transporting messages from one application to another regardless of the type of application or its location.

The Message Broker receives messages from a sending application, temporarily stores them, and then forwards them to the respective receivers. The broker can provide various functions such as message queues, topics, message routing, and transformations to ensure that messages are transmitted efficiently and securely.

Such systems are often used in distributed application landscapes to facilitate interaction and data exchange between different applications, services, or systems by enabling loosely coupled, reliable communication.

RabbitMQ is an open-source message-brokering software designed to facilitate communication between different systems, applications, or services. It acts as middleware, serving as a mediator for message exchange between different parts of an application or among different applications.

Built on the Advanced Message Queuing Protocol (AMQP), RabbitMQ allows sending, receiving, and processing messages between various systems. It acts as a broker that distributes messages between senders and receivers, ensuring messages are transmitted in a specific order, with the right priority, and reliability.

It's often used in distributed systems, microservices architectures, for decoupling applications, and implementing queues to enable communication between various components of an application. RabbitMQ facilitates information exchange among different parts of a system, contributing to improving scalability, flexibility, and reliability of applications.

A web application is a software application accessible via a web browser and operates over the internet. Unlike traditional software installed on a local computer, a web application runs on a remote server and is accessed through the user's browser.

Web applications can encompass a wide range of functions, from simple interactive pages to complex applications such as social networks, email services, online stores, productivity tools, and more. They often use a combination of different technologies like HTML, CSS, and JavaScript on the client-side (in the user's browser) as well as backend technologies like databases, server-side scripting languages (e.g., Python, PHP, Ruby), and frameworks to support functionality.

Accessing web applications via the browser makes them platform-independent, allowing them to be used from various devices with an internet connection—be it a computer, tablet, or smartphone.