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README.md

@@ -2,6 +2,8 @@
 
 a Python WSGI Web Framework. Build with Bottle and Mako.
 
+### [`Getting Starter`](pages/getting-starter)
+
 ## License
 
 CostaPy

_sidebar.md

@@ -35,3 +35,4 @@
 * Requirement
   * [git](pages/requirement/git.md)
   * [venv](pages/requirement/venv.md)
+  * [pip](pages/requirement/pip.md)

pages/getting-starter.md

@@ -2,7 +2,7 @@
 
 ## Requirement
 
-You need a [git](pages/requirement/git.md), `python`, `pip`, and [venv](pages/requirement/venv.md) before using CostaPy.
+You need a [git](pages/requirement/git.md), `python`, [pip](pages/requirement/pip.md), and [venv](pages/requirement/venv.md) before using CostaPy.
 
 Install them using the following commands on your `Debian` or `Ubuntu` system.
 
@@ -44,3 +44,6 @@ Use this command below to start the web service and it will run on port `11000`
 ```
 Here, `costapy-welcome` is the label of your service. You can replace it with any name you prefer.
 
+---
+
+[`Back to Homepage`](/) [`Learn the structure`](pages/structure)

pages/requirement/git.md

@@ -1,3 +1,3 @@
 # git
 
-Work in progress
+**Git** is a **distributed version control system (VCS)** used to **track changes in source code**, especially in software development.

pages/requirement/pip.md

@@ -0,0 +1,198 @@
+# pip
+
+`pip` is Python’s **package manager**.
+It’s the tool you use to **install, upgrade, and remove Python libraries** that aren’t included in the standard library.
+
+Think of it like:
+
+* `apt` on Debian/Ubuntu
+* `dnf` on Fedora
+* `npm` for JavaScript
+
+## What does pip do?
+
+With `pip`, you can:
+
+1. **Install packages**
+
+```bash
+pip install requests
+```
+
+2. **Upgrade packages**
+
+```bash
+pip install --upgrade requests
+```
+
+3. **Uninstall packages**
+
+```bash
+pip uninstall requests
+```
+
+4. **List installed packages**
+
+```bash
+pip list
+```
+
+5. **Install from a requirements file**
+
+```bash
+pip install -r requirements.txt
+```
+
+## Where do packages come from?
+
+By default, pip downloads packages from **PyPI** (Python Package Index):
+
+* [https://pypi.org](https://pypi.org)
+* Contains **hundreds of thousands** of Python libraries
+* Example packages: `requests`, `numpy`, `flask`, `django`, `pandas`
+
+## pip vs Python itself
+
+* **Python** → the programming language + standard library
+* **pip** → installs *extra* libraries written by the community
+
+Example:
+
+```python
+import math        # standard library (no pip needed)
+import requests    # external library (installed via pip)
+```
+
+## pip and Python versions
+
+On many systems:
+
+* `pip` → Python 2 or system default
+* `pip3` → Python 3
+
+Safer way (recommended):
+
+```bash
+python3 -m pip install requests
+```
+
+This ensures pip matches the Python version you’re using.
+
+## Virtual environments
+
+`pip` works best with **virtual environments** ([venv](pages/requirement/venv.md)) to avoid breaking system Python:
+
+```bash
+python3 -m venv venv
+source venv/bin/activate
+pip install flask
+```
+
+## What is `requirements.txt`?
+
+`requirements.txt` is a **list of Python packages** (and versions) your project depends on.
+
+Example:
+
+```txt
+flask==3.0.0
+requests>=2.31.0
+gunicorn
+```
+
+## Install dependencies from `requirements.txt`
+
+### Basic usage
+
+```bash
+pip install -r requirements.txt
+```
+
+### Safer (recommended)
+
+```bash
+python3 -m pip install -r requirements.txt
+```
+
+This ensures pip matches your Python version.
+
+## Use with a virtual environment (best practice)
+
+```bash
+python3 -m venv venv
+source venv/bin/activate
+
+pip install -r requirements.txt
+```
+
+After activation, all packages go into `venv/`.
+
+## Generate `requirements.txt` from current environment
+
+If you already installed packages:
+
+```bash
+pip freeze > requirements.txt
+```
+
+⚠️ This captures **everything** installed in the environment.
+
+## Common version formats
+
+```txt
+flask==3.0.0      # exact version (reproducible builds)
+requests>=2.31.0 # minimum version
+numpy~=1.26.0    # compatible release
+django<5.0       # version upper limit
+```
+
+## Install from multiple requirement files
+
+```bash
+pip install -r base.txt -r dev.txt
+```
+
+Useful for:
+
+* `base.txt` → production
+* `dev.txt` → development tools (pytest, black, etc.)
+
+## Requirements from Git / local path
+
+```txt
+git+https://github.com/pallets/flask.git
+-e .
+```
+
+Then install:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Debian / system Python warning (important)
+
+On Debian-based systems, **don’t install globally** unless you know what you’re doing:
+
+❌ Bad:
+
+```bash
+sudo pip install -r requirements.txt
+```
+
+✅ Good:
+
+```bash
+python3 -m venv venv
+pip install -r requirements.txt
+```
+
+## Typical workflow (TL;DR)
+
+```bash
+python3 -m venv venv
+source venv/bin/activate
+pip install -r requirements.txt
+python app.py
+```
+

pages/requirement/venv.md

@@ -14,7 +14,41 @@ When a project is no longer needed, deleting its virtual environment is straight
 
 ## How it works?
 
-When you run `python3 -m venv your_venv_directory_name`, Python creates a directory for “A mini Python install just for this project”. When you activate it with `source .venv/bin/activate`, your shell is told "When I type `python` or `pip`, use the ones inside `.venv`", Nothing else changes. So, when you type `pip install requests`, it installs only inside `.venv`. Then, you can deactivate venv with `deactivate` command.
+When you run:
+
+```sh
+python3 -m venv your_venv_directory_name
+```
+
+Python creates a directory for *“A mini Python install just for this project”*. 
+
+When you activate it with
+
+```sh
+source your_venv_directory_name/bin/activate
+```
+
+You should see
+
+```sh
+(your_venv_directory_name)
+```
+
+your shell is told *"When I type `python` or [pip](pages/requirement/pip.md), use the ones inside `your_venv_directory_name`"*, Nothing else changes. 
+
+So, when you type:
+
+```sh
+pip install requests
+```
+
+it installs only inside `your_venv_directory_name`. 
+
+Then, you can deactivate venv with this command:
+
+```sh
+deactivate
+```
 
 ## Why I add `venv` on my `gitignore`?
 

pages/structure.md

@@ -45,4 +45,6 @@ A front-end directory for pages. Use this to organize individual front-end pages
 
 By adhering to this structure, you ensure clarity, consistency, and modularity in your framework.
 
+---
 
+[`Back to Getting starter`](pages/getting-starter)