Cortex is introduced as an AI-focused note-taking application designed as a 'second brain'. It combines features of Google Docs, Notion, and Obsidian with AI. It's available on web, Windows, and Mac, with a free tier offering unlimited notes and a paid tier for full AI features.

The application's AI capabilities include changing LLMs, a library for extracting highlights from Readwise, capture features for notes and tasks, and AI chat within notes. Users can use YouTube video URLs to extract key insights. The focus mode and customizable element templates are also highlighted.

A brief mention of the video's sponsor, Sansama, a mindful task management software focused on planning and reflection.

The reviewer praises the application's speed and functionality, the elemental templates, its design for writing, AI workflows, and focus modes.

The cons include the lack of offline mode and mobile applications, and the limitations of the free plan regarding AI features. The capture mode's functionality is also criticized.

Cortex is best suited for creators, writers, and thinkers using the second brain concept. It blends features from Capacities, Tana and Obsidian. It's recommended for AI desktop users wanting to set up a note-taking system.