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Computer Science
From first principles to full stack.
The fundamentals that don't go out of date — starting with the logic and set theory that give you a precise language for thinking — plus the practical craft of full-stack web development and network engineering.
Logic & Sets
A precise language for saying exactly what you mean — and the one your code already speaks.
- Propositional logic: the algebra of true and false How propositions and the connectives ¬, ∧, ∨, → and ↔ turn everyday reasoning into an algebra your code already runs. ●●○○○ 18 min
- De Morgan's laws & simplifying conditions How to negate a compound condition correctly, and why "not (x and y)" is never "not x and not y". ●●○○○ 16 min
- Sets and set operations Unordered collections of distinct things, and the operations — union, intersection, difference — your database already runs. ●●○○○ 18 min
- Quantifiers: for all, there exists How ∀ and ∃ turn open predicates into claims with truth values, and why the order you write them in changes the meaning. ●●●○○ 18 min
- Relations & functions Ordered pairs, Cartesian products and relations — and how the extra condition that makes a relation a function underlies every lookup you write. ●●●○○ 20 min
- Valid reasoning & common fallacies Validity versus soundness, the proof patterns that actually establish things, and the argument forms that only look like they do. ●●●○○ 20 min
Fundamentals
Data, algorithms and how machines actually work.
- Big-O notation How Big-O describes the growth rate of an algorithm's cost as input size scales. ●●○○○ 15 min
- Hash tables How hash tables map keys to buckets for fast average-case lookup, and how they cope with collisions. ●●○○○ 16 min
- Binary search & binary search trees How binary search finds items in sorted data in logarithmic time, and how binary search trees keep data ordered. ●●●○○ 17 min
Software Engineering
The practices that keep code working as it grows — and as the team does.
- Version control with Git How Git models history as snapshots in a graph, why branches are cheap pointers, and how merge, rebase and good commits keep history useful. ●●○○○ 18 min
- Testing strategies Unit, integration and end-to-end tests, test doubles, TDD, flaky tests, and what coverage really measures. ●●●○○ 20 min
- Refactoring & code smells Restructuring code without changing its behaviour: small safe steps under tests, recognising common smells, and knowing when to stop. ●●●○○ 18 min
- Design principles: SOLID and beyond Cohesion and coupling as the core idea behind SOLID, DRY, YAGNI, composition and deep modules, and how these principles get misapplied. ●●●○○ 22 min
- System design fundamentals Scaling, load balancing, caching, replication, sharding, queues and an accurate CAP theorem: the core trade-offs of building systems that grow. ●●●●○ 22 min
- CI/CD and deployment Continuous integration, delivery vs deployment, trunk-based development, feature flags, safe release strategies and the four DORA metrics. ●●●○○ 18 min
- Observability: logs, metrics and traces What logs, metrics and traces are each good for, structured logging, distributed tracing, SLOs with error budgets, and symptom-based alerting. ●●●○○ 18 min
- Technical debt & architecture decisions Cunningham's debt metaphor and its misuse, deliberate vs accidental debt, ADRs, monoliths vs microservices, and Conway's law. ●●●○○ 18 min
Full-Stack Web
Building and shipping real web applications.
- HTTP request & response The anatomy of HTTP requests and responses, including methods, status codes, headers, and statelessness. ●●○○○ 16 min
- REST API design Principles of REST API design including resources, verb-to-CRUD mapping, status codes, statelessness, and idempotency. ●●●○○ 18 min
- SQL fundamentals The relational model and core SQL operations including SELECT, WHERE, JOIN, GROUP BY, and keys. ●●○○○ 18 min
Network Engineering
How packets get from here to there.
Related reading
Books from the shelf that go deeper on this.