Developer glossary

Short definitions of terms used across this blog, each linked to the post that explains it in depth.

CORS (Cross-Origin Resource Sharing): An HTTP-header based mechanism that lets a server say which other origins a browser may load its resources from. Without it, browsers block cross-origin reads by default. Read: What is CORS
Preflight request: An OPTIONS request the browser sends before a non-simple cross-origin request, such as one using PUT or a custom header, to ask the server for permission. The answer can be cached with Access-Control-Max-Age. Read: What is CORS
HTTP security headers: Response headers such as Content-Security-Policy, Strict-Transport-Security and X-Content-Type-Options that instruct the browser to enable protections for your site. Read: How to use security headers
NAT gateway: An AWS managed service placed in a public subnet that lets resources in private subnets, such as a VPC-attached Lambda function, make outbound connections to the internet through the internet gateway. Read: Lambda function in a VPC
VPC endpoint: A private connection from a VPC to an AWS service that avoids a NAT gateway. Gateway endpoints for S3 and DynamoDB have no charge; interface endpoints are billed per hour and per GB. Read: NAT gateway vs VPC endpoint costs
Amazon CloudFront: AWS's content delivery network, which serves cached copies of static and dynamic content from edge locations. Hosting a single-page app on it needs custom error responses so client-side routes do not return 403 or 404. Read: Hosting an SPA on CloudFront
MCP (Model Context Protocol): An open protocol, introduced by Anthropic in November 2024, that standardizes how applications provide context and tools to large language models, using JSON-RPC 2.0 between a client and a server. Read: Building an MCP server
Shamir's Secret Sharing: A cryptographic scheme that splits a secret into n shares so that any k of them can rebuild it, while k-1 shares reveal nothing about it. Read: Breaking bad habits with Shamir's Secret Sharing
git bisect: A Git command that binary-searches your commit history, asking you to mark commits good or bad, to find the exact commit that introduced a bug. Read: Git bisect
Pi-hole: A network-level DNS sinkhole, typically run on a Raspberry Pi, that blocks ads and unwanted domains for every device on your network. Read: Ad blocker for your whole network
Steganography: The practice of concealing a message inside another medium, such as text, an image, audio, video or network traffic, so that the existence of the message is hidden. Read: Steganography
SO_REUSEADDR: A socket option that lets a process bind to an address and port that is still in use in certain states. It is why Docker can appear to bind a port already used by a host process. Read: Port sharing and SO_REUSEADDR in Docker
Selenium WebDriver: A browser automation library that controls a real browser from code, used for testing and for automating repetitive web tasks. Read: Web automation with Selenium
ngrok: A tunneling service that exposes a local or home-network service, such as a Raspberry Pi web interface or SSH, to the internet through a public URL. Read: Access a Raspberry Pi with ngrok
ffmpeg.wasm: FFmpeg compiled to WebAssembly so video and audio can be converted directly in the browser without uploading files to a server. Read: Convert video to GIF with FFmpeg