HTML (Hypertext Markup Language) and CSS (Cascading Style Sheets) are not typically classified as programming languages because they do not have the full capabilities of traditional programming languages like Python, Java, or C++. 

Here are a few key reasons why HTML and CSS are often considered markup and styling languages rather than full programming languages:

- Declarative vs. Imperative: HTML and CSS are declarative languages, meaning that they describe the structure and presentation of content rather than specifying a sequence of steps to achieve a result. In contrast, programming languages are typically imperative, where you write code that specifies exactly how a task should be performed.

- Limited Logic: HTML is primarily used for structuring content on a webpage, while CSS is used for styling that content. While CSS does involve some logic for styling elements based on conditions, it lacks the full range of logical operations and control flow structures found in programming languages.

- Interactivity: One of the key aspects of programming languages is the ability to create interactive applications by defining algorithms and logic. HTML and CSS are not designed for this purpose; they are mainly used for defining the layout and appearance of web content.

- Execution: HTML and CSS are interpreted by web browsers to render web pages, whereas programming languages are typically compiled or interpreted by a runtime environment to execute instructions and perform computations.

While HTML and CSS are essential for web development and are crucial for creating visually appealing and structured web pages, they are not considered programming languages due to their limited computational abilities and the nature of their use in web development.