diff --git a/1_understanding_a_computer.md b/1_understanding_a_computer.md
index 56a29bc8e1556eff4ec4ec552ff83d21965fab4c..4dd52a0a0f5e9763a5516f7fc62090da79aa7333 100644
--- a/1_understanding_a_computer.md
+++ b/1_understanding_a_computer.md
@@ -17,7 +17,7 @@ Objective: understand the relations between the different components of a comput
 
 ---
 
-# Computer model: an universal Turing machine
+# Computer model: universal Turing machine
 
 
 ![width:20% height:20%](./img/lego_turing_machine.jpg)
@@ -32,9 +32,9 @@ Objective: understand the relations between the different components of a comput
 ## Memory
 
 ### RAM (Random Access Memory)
-![RAM](./img/Swissbit_2GB_PC2-5300U-555.jpg/220px-Swissbit_2GB_PC2-5300U-555.jpg)
+![RAM](./img/220px-Swissbit_2GB_PC2-5300U-555.jpg)
 
-### HDD (Hard Disk Drive) / SSD (Solid State Drive) 
+### HDD (Hard Disk Drive) / SSD (Solid-State Drive) 
 ![HDD](./img/220px-Laptop-hard-drive-exposed.jpg)
 ![SSD](./img/220px-SSD_Samsung_960_PRO_512GB_-_front_and_back_-_2018-05-27.jpg)
 
@@ -74,7 +74,7 @@ Objective: understand the relations between the different components of a comput
 
 Advantages:
 
-- Ability to use large disks partitions (over 2 TB) with a GUID Partition Table (GPT)
+- Ability to use large-disk partitions (over 2 TB) with a GUID Partition Table (GPT)
 - CPU-independent architecture
 - CPU-independent drivers
 - Flexible pre-OS environment, including network capability
@@ -116,7 +116,7 @@ The philosophy of UNIX is to have a large number of small software which do few
 
 # GNU/Linux
 
-Linux is the name of the Kernel which a software, to get a full OS, Linux is part of the [GNU Project](https://www.gnu.org/).
+Linux is the name of the kernel which software, to get a full OS, Linux is part of the [GNU Project](https://www.gnu.org/).
 
 The GNU with Richard Stallman introduced the notion of Free Software:
 1. The freedom to run the program as you wish, for any purpose.
@@ -126,22 +126,22 @@ The GNU with Richard Stallman introduced the notion of Free Software:
 
 ![Richard Stallman](https://audio-video.gnu.org/video/TEDxGE2014_Stallman05_LQ.webm)
 
-You can find a [list of software licences](https://www.gnu.org/licenses/license-list.html)
+You can find a [list of software licenses](https://www.gnu.org/licenses/license-list.html)
 
 # (First) step with GNU/Linux
 
 You first need to connect to [https://biosphere.france-bioinformatique.fr/](https://biosphere.france-bioinformatique.fr/).
 
-Go to [RAINBio the catalogue of Appliances](https://biosphere.france-bioinformatique.fr/catalogue/) and start the [UNIX Biocomputing](https://biosphere.france-bioinformatique.fr/catalogue/appliance/173/) appliance. An appliance is a virtual machine with preinstalled softwares.
+Go to [RAINBio the catalogue of appliances](https://biosphere.france-bioinformatique.fr/catalogue/) and start the [UNIX Biocomputing](https://biosphere.france-bioinformatique.fr/catalogue/appliance/173/) appliance. An appliance is a virtual machine with preinstalled software.
 
 Then go to the [myVM tab](https://biosphere.france-bioinformatique.fr/cloud/) and wait for your appliance to start.
 
-Then click on the params link **Params** to get your login and password
+Then click on the link **Params** to get your login and password.
 ![Params](ifb_params.png)
 
 You can then open the **https** link.
 
-And go the the next session [2 first steps in a terminal](2_first_steps_in_a_terminal.html)
+And go to the next session [2 first steps in a terminal.](2_first_steps_in_a_terminal.html)