Consensus
Algorithms for agreeing on a single value across nodes.
Concept index
Topics
Most pages on the site touch several concepts. This page goes the other way — pick a concept, see every page that covers it. Use it to jump sideways: read the Spanner paper, then the consistent-hashing simulator, then the load-balancing deep dive on Maglev, all under one tag.
Good places to start
Eight topics that anchor the rest.
Pick one if you don't know where to begin. Each one of these connects to a half-dozen other topics on this page.
Consensus
Algorithms for agreeing on a single value across nodes.
CAP & PACELC
The trade-off between consistency, availability, and partition tolerance.
B-trees
The canonical disk-backed index structure used by most relational databases.
Caching
Where each layer — browser, CDN, app, database — earns its keep.
TCP/IP
Reliable byte streams over best-effort packet delivery.
Tail latency
Why p99 matters more than the average when requests fan out.
Sharding
Splitting a dataset across nodes — by range, hash, or directory.
Isolation levels
What every "Serializable" actually means, and where the anomalies hide.
Distributed systems
8 topics
CAP & PACELC
The trade-off between consistency, availability, and partition tolerance.
Consistent hashing
Mapping keys to nodes so adding or removing a node only moves K/N keys.
Logical clocks
Ordering events without synchronised real time.
CRDTs
Data types where concurrent updates merge without coordination.
Replication
Strategies for copying data — leader-follower, multi-master, gossip.
Sagas & long-lived workflows
Replacing distributed transactions with idempotent steps and compensations.
Byzantine fault tolerance
Consensus that survives malicious — not just crashed — participants.
Storage & databases
9 topics
B-trees
The canonical disk-backed index structure used by most relational databases.
LSM-trees
Write-optimised storage — appends to memory, merges to sorted disk runs.
Write-ahead logging & recovery
How databases survive crashes — log first, page later.
Isolation levels
What every "Serializable" actually means, and where the anomalies hide.
MVCC
Multi-version concurrency control — every read sees a snapshot.
Caching
Where each layer — browser, CDN, app, database — earns its keep.
Sharding
Splitting a dataset across nodes — by range, hash, or directory.
Column stores
Why analytical queries scan columns, not rows — and 10× faster.
Distributed transactions
When two-phase commit blocks, sagas help, and Spanner+Calvin do something different.
Networking
8 topics
TCP/IP
Reliable byte streams over best-effort packet delivery.
TLS & HTTPS
The handshake under the lock — keys, certificates, forward secrecy.
DNS
How names resolve from your resolver out to the root.
HTTP
Request, response, methods, headers, status codes — and the three major versions.
QUIC & HTTP/3
TCP's head-of-line problem, solved at the protocol level.
BGP
How the internet learns where to send a packet.
Load balancing
L4 vs L7, algorithms, anycast, consistent hashing, graceful drain.
CDN
PoPs, anycast, cache keys, origin shielding — the internet's middle layer.
Performance
4 topics
Tail latency
Why p99 matters more than the average when requests fan out.
USE & RED methods
Diagnosing systems from the outside — Brendan Gregg's USE, Tom Wilkie's RED.
Queueing theory
Little's Law and the math behind every saturation curve.
Profiling
Finding where the CPU actually goes — sampling, instrumentation, flame graphs.
OS & runtimes
4 topics
Memory & GC
Stack, heap, arena, garbage collection — where every malloc actually goes.
Concurrency
Threads, channels, event loops, lock-free structures.
Containers
Namespaces, cgroups, layers, runtimes — the Linux process with its own world.
Unix & systems history
The papers and architectures that shaped modern operating systems.
Security
1 topic
OAuth & OpenID Connect
Letting an app act on the user's behalf without their password.
Languages
1 topic
Go
Channels, goroutines, the scheduler, escape analysis, interfaces.
Algorithms
4 topics
Graph algorithms
BFS, DFS, shortest paths, max-flow, topological sort.
Dynamic programming
Overlapping subproblems, memoisation, the canonical patterns.
Data structures
Trees, hashes, heaps, tries — operations and Big-O for each.
Coding patterns
20 canonical patterns for the interview class of algorithm problems.
Kubernetes
1 topic
Kubernetes internals
API server, scheduler, kubelet, etcd, CRDs.
People & papers
2 topics
Lamport
Logical clocks, Paxos, Byzantine Generals, TLA+.
Google systems papers
GFS, MapReduce, Bigtable, Spanner, F1, Borg, Maglev.
Missing a topic?
This index is hand-curated. If you searched for something and didn't find it, it probably isn't covered yet — or it's covered under a different name. Try ⌘K search as the fallback, or browse the glossary for a quick definition.
Looking for a study order, not a tag dump? The senior-SWE roadmap walks the same topics in a sensible sequence.
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