pip install -r requirements.txt

The command pip install -r requirements.txt is used in Python projects to install all the dependencies listed in the requirements.txt file.

Here's what each part means:

• pip: Python's package installer, used to install libraries and packages.
• install: The command telling pip to install the specified packages.
• -r requirements.txt: This option specifies the file (requirements.txt) that contains a list of dependencies (libraries or packages) required for the project. Each line in the file typically contains the name of a package and optionally its version (e.g., requests==2.25.1).

So, running this command installs all the dependencies your project needs, making it easier to replicate your project's environment.