Apple Intelligence is Apple's built-in AI system that helps users write, communicate, edit photos, and complete everyday tasks across iPhone apps. Only iPhone 15 Pro and newer support it, a hardware limit rather than a marketing choice. In 2026, the system behind those features has quietly shifted: Apple now leans on an outside AI partner for its hardest reasoning tasks. Siri understands what's on screen, maintains conversational context, and performs actions across multiple apps. Writing Tools lives inside Mail, Notes, and Messages, rewriting drafts and fixing tone. In Photos, Clean Up erases people or objects from the background, and search works by plain description. Live Translation handles real-time conversation inside Messages, Phone, and FaceTime. Genmoji and Image Playground turn a text description into a custom image or emoji. Notification Summaries condense a busy thread into one line. These features run on a system layer built into iOS itself. Simple tasks run right on the iPhone's Neural Engine. Heavier requests travel to Private Cloud Compute, Apple's server system designed to process data and then discard it rather than store it. Some work stays on the phone while other moves to Apple's own servers. That split is the core idea, and it holds steady no matter which outside model powers the cloud side in a given year. A foundation model is a large AI system trained on huge amounts of text and images. Apple splits the job instead.