What are the classification problems in machine learning?

What is classification in machine learning?

What is data structure and its classification?

What are the classification of data structures?

How many classes are there in classification?

What is variable and its classification?

What are the classifications of property?

What is property classification?

what is classification of elemental impurities? what is risk assement in elemental impurities?

What are some common evaluation metrics for classification and regression problems?

How would you build a simple classification model?