A developer's deep dive into Zig's memory layout rules emerged from Andrew Kelley's data-oriented design talk. The article decodes how the language calculates @alignOf and @sizeOf for primitives, structs, and unions. It reveals that alignment and size are always powers of two, a constraint driven by CPU architecture for performance.

For primitives like `u8` or `f64`, size matches alignment. Structs require careful padding to respect field alignments, which can drastically change memory footprint. The author contrasts `ABAB` and `ABBA` struct layouts, showing how field order impacts efficiency. This knowledge is critical for writing performant, cache-friendly code.

Zig's compiler automatically minimizes struct padding unless `extern` is used for C ABI compatibility. Mastering these formulas lets developers optimize data structures for memory-constrained systems. The practical application is direct: smaller, faster programs. This aligns with Zig's philosophy of explicit control over low-level details.