Added Kafka key concepts from blog into Apache Kafka® glossary for SEO enhancement.

_toc.yml

@@ -318,6 +318,7 @@ entries:
       - file: docs/products/kafka/howto/fake-sample-data
         title: Sample data generator
       - file: docs/products/kafka/concepts
+        title: Concepts
         entries:
           - file: docs/products/kafka/concepts/upgrade-procedure
             title: Upgrade procedure

docs/products/kafka/concepts.rst

@@ -1,6 +1,83 @@
-Concepts
-========
+Apache Kafka® concepts
+======================
 
-Explanations and supporting concepts to help you succeed with Aiven for Apache Kafka®.
+A comprehensive glossary of essential Apache Kafka® terms and their meanings.
 
-.. tableofcontents::
+.. _Broker:
+
+Broker
+------
+
+A server that operates Apache Kafka, responsible for message storage, processing, and delivery. Typically part of a cluster for enhanced scalability and reliability, each broker functions independently but is integral to Kafka's overall operations, separate from tools like Apache Kafka Connect.
+
+Consumer
+--------
+
+An application that reads data from Apache Kafka, often processing or acting upon it. Various tools used with Apache Kafka ultimately function as either a producer or a consumer when communicating with Apache Kafka.
+
+Consumer groups
+---------------
+
+Groups of consumers in Apache Kafka are used to scale beyond a single application instance. Multiple instances of an application coordinate to handle messages, with each group allocated to different partitions for even workload distribution.
+
+Event-driven architecture
+-------------------------
+
+Application architecture centered around responding to and processing events.
+
+.. _Event:
+
+Event
+-----
+
+A single discrete data unit in Apache Kafka, consisting of a ``value`` (the message body) and often a ``key`` (for quick identification) and ``headers`` (metadata about the message).
+
+Kafka node
+----------
+
+See :ref:`Broker`
+
+Kafka server
+------------
+
+See :ref:`Broker`
+
+Message
+-------
+
+See :ref:`Event`
+
+Partitioning
+------------
+
+A method used by Apache Kafka to distribute a topic across multiple servers. Each server acts as the ``leader`` for a partition, ensuring data sharding and message order within each partition.
+
+Producer
+--------
+
+An application that writes data into Apache Kafka without concern for the data's consumers. The data can range from well-structured to simple text, often accompanied by metadata.
+
+Pub/sub
+-------
+
+A publish-subscribe messaging architecture where messages are broadcasted by publishers and received by any listening subscribers, unlike point-to-point systems.
+
+Queueing
+--------
+
+A messaging system where messages are sent and received in the order they are produced. Apache Kafka maintains a watermark for each consumer to track the most recent message read.
+
+Record
+------
+
+See :ref:`Event`
+
+Replication
+-----------
+
+Apache Kafka's feature for data replication across multiple servers, ensuring data preservation even if a server fails. This is configurable per topic.
+
+Topic
+-----
+
+Logical channels in Apache Kafka through which messages are organized. Topics are named in a human-readable manner, like ``sensor-readings`` or ``kubernetes-logs``.