Intermediate terms
HTTP Content Negotiation
1
The HTTP mechanism by which clients declare what formats, languages, and encodings they accept (Accept, Accept-Language, Accept-Encoding) and servers respond with the best match — or 406 Not Acceptable if none fits.
2mo ago
api_design intermediate
HTTP/2 Server Push & Early Hints
HTTP/2 Server Push lets a server proactively send assets (CSS, JS, fonts) before the browser requests them. 103 Early Hints is its practical successor — sending Link preload headers before the full response is ready.
2mo ago
networking intermediate
Hoisting — var, let, const and function
ES5
JavaScript hoists declarations to the top of their scope — var and function declarations are fully hoisted, while let and const are hoisted but remain in the Temporal Dead Zone until their declaration line.
3mo ago
javascript intermediate
History API — SPA Routing with PHP Backend
HTML5
history.pushState and popstate enable URL changes without page reload — used for SPA routing while keeping PHP as the backend.
3mo ago
javascript intermediate
Hashing Algorithms Deep Dive
PHP 7.2+
Comparing hash functions for different use cases — MD5/SHA-1 (broken, legacy), SHA-256/BLAKE3 (data integrity), bcrypt/Argon2 (passwords), xxHash/MurmurHash (non-cryptographic, fast).
3mo ago
algorithms intermediate
How CDNs Work
1
CDNs use Anycast routing and distributed edge PoPs to serve content from the nearest location — reducing latency from 300ms to 5ms for cached responses.
3mo ago
networking intermediate
HTTP Request-Response Cycle
1
The complete lifecycle of an HTTP request — DNS resolution, TCP connection, TLS handshake, request transmission, server processing, and response delivery.
3mo ago
networking intermediate
Hash Table
PHP 5.0+
1
A data structure that maps keys to values using a hash function, providing amortised O(1) average-case lookups, insertions, and deletions.
3mo ago
data_structures intermediate
hash_equals()
PHP 5.6+
1
Constant-time string comparison that prevents timing attacks when validating tokens and CSRF values.
3mo ago
php intermediate
Header Injection
PHP 5.0+
User input included in an HTTP response header without stripping newlines enables response splitting and redirect hijacking.
CWE-113 OWASP A3:2021
3mo ago
security intermediate
6.1
Heaps & Priority Queues
PHP 5.3+ A tree-based structure satisfying the heap property — min-heap: parent ≤ children; max-heap: parent ≥ children — enabling O(1) peek and O(log n) insert/extract for priority queues.
3mo ago
data_structures intermediate
HMAC (Hash-based Message Authentication Code)
PHP 5.1+
1
A keyed hash that verifies both the integrity and authenticity of a message — only someone with the secret key can produce or verify it.
OWASP A2:2021
3mo ago
security intermediate
Host Header Injection
PHP 5.0+
A manipulated HTTP Host header is used by the application to generate URLs, enabling cache poisoning, password-reset hijacking, or SSRF.
CWE-116 OWASP A3:2021
3mo ago
security intermediate
7.5
HTTP Caching (ETags, Cache-Control)
Standard HTTP headers that instruct browsers and intermediary caches on how long to cache responses and when to revalidate.
3mo ago
performance intermediate
HTTP Methods — Idempotency & Safety
Safe methods (GET, HEAD) have no side effects. Idempotent methods (GET, PUT, DELETE, HEAD, OPTIONS) produce the same result regardless of how many times they are called.
3mo ago
networking intermediate
HTTP Parameter Pollution
PHP 5.0+
Submitting duplicate HTTP parameters exploits inconsistencies in how servers and applications parse repeated keys.
CWE-235 OWASP A3:2021
3mo ago
security intermediate
6.5
HTTP Security Headers Checklist
A set of response headers that instruct browsers to enforce security policies — CSP, HSTS, X-Frame-Options, X-Content-Type-Options, and Permissions-Policy.
3mo ago
security intermediate
HTTP/2 & HTTP/3
1
Modern HTTP protocol versions that deliver significant performance gains via multiplexing, header compression, and (HTTP/3) UDP transport.
3mo ago
performance intermediate
Hyrum's Law
"With enough API users, all observable behaviours will be depended upon, regardless of documented contract" — implicit behaviours become de facto API.
3mo ago
general intermediate