Master Coding Skills &
System Design.

Learn MySQL stored procedures and functions — parameters, IF/CASE logic, loops, transactions, and the difference between procedures and functions.

Master the most important PHP design patterns — Singleton, Factory, Observer, Strategy, Decorator, and Repository with complete code examples.

Master CSS Flexbox — every container and item property explained, alignment, the flex shorthand, and common real-world layout patterns.

Master sorting algorithms — bubble sort, merge sort, quick sort with Python code, step-by-step traces, and complexity comparison table.

Master the JavaScript this keyword — the 4 binding rules, common pitfalls, arrow functions vs regular functions, and call/apply/bind.

Master SQL window functions — ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD with PARTITION BY. The most asked advanced SQL topic in data and backend interviews.

Master Python decorators — how they work, functools.wraps, decorators with arguments, class-based decorators, and practical examples like memoize and rate limiter.

Learn Composer from scratch — installing packages, PSR-4 autoloading, version constraints, and composer.lock for reproducible builds.

Design a real-time chat system for 500 million users — WebSockets vs polling, Kafka message queue, Cassandra storage, presence service and push notifications.