ShieldFont is an experimental open-source system designed to make large-scale AI scraping more costly by serving altered HTML while using OpenType font substitutions to display the original text to human readers. This guide explains how ShieldFont works, what its official tests actually prove, why OCR and font analysis can bypass it, and the SEO, accessibility, copy-and-paste, and language-support trade-offs creators need to consider. It also covers Twitch’s AI training opt-out, current U.S. policy discussions, and practical alternatives such as robots.txt, CDN, and WAF controls.