I often see m_ prefix used for variables (m_World,m_Sprites,...) in tutorials, examples and other code mainly related
The m_ prefix is often used for member variables - I think its main advantage is that it helps create a clear distinction between a public property and the private member variable backing it:
int m_something
public int Something => this.m_something;
It can help to have a consistent naming convention for backing variables, and the m_ prefix is one way of doing that - one that works in case-insensitive languages.
How useful this is depends on the languages and the tools that you're using. Modern IDEs with strong refactor tools and intellisense have less need for conventions like this, and it's certainly not the only way of doing this, but it's worth being aware of the practice in any case.