Could you explain what is meant by the term 'code pollution' and how it affects development?

The term "code pollution" usually refers to the presence of unnecessary, unstructured, or poorly organized elements in the codebase that hinder understanding, maintenance, and development of the program. These can include:

• Global variables used everywhere, creating dependencies.
• Redundant or duplicated code sections.
• Unclear variable and function names.
• Excessive comments or their absence.
• Use of outdated constructs.

In PHP, code pollution can lead to difficulties in scaling the project, increased bugs, and reduced team productivity. To avoid pollution, it is recommended to adhere to clean code principles, use namespaces, encapsulation, and follow coding standards.