Learn the whole of computer science.

Explore by field

• Programming — fundamentals, languages, and object-oriented design
• Operating systems — processes, threads, scheduling, synchronization, and memory
• Networking — IP, routing, transport, HTTP, and secure communication
• Databases — relational modeling, SQL, joins, indexes, and transactions
• Full topic library — search across the complete catalog

Start with these topics

• What is Programming? — Writing precise instructions a machine can execute, and choosing the data those instructions work on.
• Arrays — A contiguous block of same-sized elements. Constant-time indexing, cache-friendly scans, and costly middle inserts.
• Big-O and Complexity — How an algorithm's cost grows with input size, ignoring constants. The language for comparing solutions before you run them.
• Processes — An OS abstraction: address space, at least one thread, and a pile of kernel metadata.
• CPU Scheduling — The policy that picks the next ready thread. Fairness, latency, and throughput trade off.
• OSI Model — Seven layers of function, from photons to application messages. The shared language of networking.
• TCP — Reliable, ordered, congestion-controlled byte streams between two ports.
• SQL — The declarative language of relational databases: SELECT describes the result, not the plan.
• Transactions — A grouping of reads and writes that should succeed or fail as a unit.
• Indexes — Auxiliary structures (usually B+ trees) that make predicates cheap at the cost of writes and space.

Explore the curriculum

• Operating Systems — 43 topics
• Computer Networks — 71 topics
• Databases / DBMS — 37 topics
• Programming Fundamentals — 11 topics
• Programming Languages — 9 topics
• Object-Oriented Design — 8 topics
• Data Structures & Algorithms — 16 topics

A repeatable learning method

1. Understand the definition and the guarantee the concept provides.
2. Trace a small example or state transition from input to result.
3. Test an edge case and explain the trade-off or failure mode.

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