diff --git a/content/img/containerized_application.graphml b/content/img/containerized_application.graphml
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+ Container
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+ Container
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+ Home computer
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+ Home computer
+OS
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+ Container software
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+ Container software
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+ applications are exactly the same
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+ =
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+ Because containers are the same
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+ OS in container
+image
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+ Application
+in container image
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diff --git a/content/img/containerized_application.svg b/content/img/containerized_application.svg
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+++ b/content/img/containerized_application.svg
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+
diff --git a/content/img/normal_application.graphml b/content/img/normal_application.graphml
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+ Application
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+ HPC cluster OS
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+ ≠
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+ Because operating systems differ
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diff --git a/content/img/normal_application.svg b/content/img/normal_application.svg
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diff --git a/content/intro_and_motivation.rst b/content/intro_and_motivation.rst
index a1c6abd..7f39d85 100644
--- a/content/intro_and_motivation.rst
+++ b/content/intro_and_motivation.rst
@@ -7,5 +7,57 @@ Intro about containers (on HPC)
* Learn about the possibilities with containers on HPC clusters
-Here some motivational paragraphs and some (many!) references.
+What even is a container?
+-------------------------
+
+Containers take their name from shipping containers:
+
+.. figure:: https://upload.wikimedia.org/wikipedia/commons/3/36/Shipping_container%2C_Bellarena_-_geograph.org.uk_-_1859736.jpg
+
+ Figure 1: A shipping container in its natural habitat
+
+This analogue is based on the idea is that containers have a barrier
+between the insides of the container and outside of the container.
+This makes shipping them between ports easy.
+
+Based on this analogue one might think that the container is just a
+storage format.
+
+Instead it is a way of running **an application in a self-contained
+environment with all the tools that this specific application needs**.
+
+More traditional container launchers like docker, podman and kubernetes
+also manage containers' resource usage and various other aspects. When
+using apptainer, we do not need to worry about these features.
+
+.. admonition:: How traditional containers work
+
+ Traditional containers use linux namespaces.
+
+Let's consider the following case:
+
+1. User installs and runs an application on a their home computer
+2. They want to run the exact same application on their HPC cluster
+3. The operating system / available software is different on the HPC cluster
+4. Even if the program runs, it is necessarily not the **exact same program** as operating system has changed
+
+.. figure:: img/normal_application.svg
+
+With containers the user would run the exact same container on both systems:
+
+.. figure:: img/containerized_application.svg
+
+.. admonition:: Key point
+
+ Containers are a way of launching an application in a self-contained
+ environment.
+
+ Container can refer to:
+
+
+Image sources
+-------------
+
+- Shipping container, Bellarena by Rossographer, `CC BY-SA 2.0 `__, via `Wikimedia Commons `__
+