diff --git a/css/style.css b/css/style.css
index 05ae57b0bc9d2624b36338545f73fb14d8b02e01..778eee3af854c6cc2d2efbdb2aaed12020d584b3 100644
--- a/css/style.css
+++ b/css/style.css
@@ -21,7 +21,7 @@
   margin: 10px 0px;
   background: rgba(255, 255, 255, 0.12);
   border: 0px solid #000;
-  box-shadow: 0 0 5px rgba(0, 0, 0, 0.15);
+  box-shadow: 0 0 0px rgba(0, 0, 0, 0.15);
   -webkit-transition: all .2s linear;
   -moz-transition: all .2s linear;
   -ms-transition: all .2s linear;
diff --git a/img/branch-0-master.png b/img/branch-0-master.png
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diff --git a/img/history_tracking.pxm b/img/history_tracking.pxm
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diff --git a/img/history_tracking_collaboration.png b/img/history_tracking_collaboration.png
deleted file mode 100644
index 2dda29b1822762dab311df121289ea1b7614005c..0000000000000000000000000000000000000000
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diff --git a/img/manual_version_control.png b/img/manual_version_control.png
deleted file mode 100644
index 0d794b1c86fe049cdf3ca6359f8da9c8af6efb1d..0000000000000000000000000000000000000000
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diff --git a/slides/branches.md b/slides/branches.md
index 69f185de3ba65198c896886d08cdf6888819e2d9..4cf120ff7cf7a69aa35ba99f3c1747ff84b3f64b 100644
--- a/slides/branches.md
+++ b/slides/branches.md
@@ -3,7 +3,7 @@
 Branch-off within the same repository in order to stay safe!
 
 The master branch:
-<img src="img/branch-0-master.png" class="as-is" />
+<img src="img/branch-master.png" class="branch-master" />
 
 
 ## One branch per feature
@@ -14,7 +14,7 @@ $ git checkout -b matrix_vect_mult_myName
 ```
 The `-b` flag creates the branch.
 
-<img src="img/branch-1-checkout-b.png" class="as-is" />
+<img src="img/branch-create.png" class="branch-create" />
 
 
 ## Switch between branches
@@ -40,22 +40,23 @@ You can switch back to master with
 $ git checkout master
 ```
 
-<div class="fragment">
+
 <br>
 You can use the 5 essential commands as before.
 
 Only difference: you are on your own branch.
 
+<img src="img/branch-commit.png" class="branch-commit" />
+
 
 ## Merge a branch
 
 If you want your feature on the `develop` or `master` branches, merge!
 
-<br>
 **submit a MR or a PR** via the Github/Gitlab interface.
 
+<img src="img/branch-merge.png" class="branch-merge" />
 <div class="fragment">
-<br>
 **ADVANCED**: You can see the differences between branches
 ```sh
 $ git diff master..matrix_vect_mult_myName
diff --git a/slides/essential_commands.md b/slides/essential_commands.md
index f1e3117782c2eaebcfa83488870938a4aecc5424..2b29de7d5970cbee547b59515fcbca1e1eb51d93 100644
--- a/slides/essential_commands.md
+++ b/slides/essential_commands.md
@@ -95,7 +95,7 @@ $ git pull
 ```
 
 
-## Push your file to the folder
+## Push your file to the repository
 
 ```sh
 $ git push
diff --git a/slides/forks.md b/slides/forks.md
index 0249eadec9b8b96f8ce2be6134e3b94652f8c1a8..79ad368dd32de4c7afb9e3b9575c7f64e5cc933b 100644
--- a/slides/forks.md
+++ b/slides/forks.md
@@ -1,35 +1,78 @@
-## Fork
+## Forks
 
-<img src="img/remote-0-master.png" class="as-is" />
+You **fork** when you want to work on a public repository or a protected repository.
 
-<img src="img/remote-1-remote.png" class="as-is" />
+Remember:
 
-## Ajouter une _remote_
+- A **fork** is your own **copy** of a repository.
+- A **fork** can have multiple **branches**
+- A **fork** is not a **branch**, but can have multiple **branches**.
 
-```shell
-$ git remote add origin git@github.com:<user>/<proj>.git
-$ git remote -v
+
+## Fork on GitLab
+
+
+## Fork on GitHub
+
+
+## Clone your fork
+
+Clone first:
+```sh
+$ git clone https://git-r3lab.uni.lu/myGroup/myRepo.git forkMyRepo
 ```
 
+<br>
+then, you can change to the directory:
+```sh
+$ cd forkMyRepo
+```
 
-```shell
-$ git push origin master
+
+## Add the address of the original repository
+
+Add the `upstream` (where you copied from)
+```sh
+$ git remote add upstream https://git-r3lab.uni.lu/origGroup/origRepo.git
 ```
-<img src="img/remote-2-push.png" class="as-is" />
 
+<br>
+You can then check whether the remote address is set correctly:
+```sh
+$ git remote -v
+```
+<!-- <img src="img/remote-0-master.png" class="as-is" /> //-->
+<!-- <img src="img/remote-1-remote.png" class="as-is" /> //-->
+<!--- <img src="img/remote-2-push.png" class="as-is" /> //-->
 
-## Récupérer les changements
 
-```shell
-$ git checkout master     # Aller sur la branche master
-$ git status              # Est-ce propre? (Bien sûr!)
-$ git pull origin master  # Récupérer le travail
-                          # de l'équipe
+## Synchronize your fork
+
+```sh
+$ git checkout master
+$ git status
 ```
 
+<div class="fragment">
+<br>
+Fetch the changes from upstream (similar to pull)
+```sh      
+$ git fetch upstream
+```
 
-## _Sync Branch_
-Terminologie de l'application GitHub
+<div class="fragment">
+<br>
+Merge the retrieved changes
+```sh
+$ git merge upstream/master
+```
+
+<div class="fragment">
+<br>
+Push the changes to your own fork:
+```sh
+$ git push origin master
+```
 
 
 ## Pull/Merge Requests
diff --git a/slides/installation.md b/slides/installation.md
index deff9b919f26417ff6ac6c38f76df4a7e01856bc..b33ba488830d5789c9c3f25e1446c07b402ccae7 100644
--- a/slides/installation.md
+++ b/slides/installation.md
@@ -44,7 +44,7 @@ $ git config --global user.email "first.last@uni.lu"
 
 ## Does it work?
 
-```shell
+```sh
 $ git --version
 # git version 2.10.0
 ```
@@ -77,7 +77,7 @@ Any other rudimentary method such as
 shall **be avoided**!
 
 
-## How do I `clone` any other repository?
+## How do I `clone` a repository?
 
 You can clone any other repository with:
 ```sh