What is a 'star schema' in data warehouse design?

In a Star Schema the Fact Table stores measurable, quantitative data (transaction_amount, loan_amount, quantity) with foreign keys to dimensions. Dimension Tables are descriptive in context (Customer_dim: name, age, city; Branch_dim: branch_name, region; Date_dim: day, month, quarter, year; Product_dim: product_name, category).  Advantages: Simple queries, fast read performance (fewer joins than normalized OLTP), easy for BI tools.  Banking example: Transaction fact table linked to Customer, Branch, Account, Date, and Channel dimensions enables questions like "What is the total transaction value by branch, product, and quarter?"