Core Insights - The article reflects on the missed opportunity of creating a photo-sharing platform similar to Instagram, highlighting the importance of execution and timing in the tech industry [1][4][47]. Technical Architecture - Instagram's initial architecture was designed to be simple, avoiding reinventing the wheel and utilizing reliable technologies [9][7]. - The application was built on Amazon EC2 and Ubuntu Linux, with a focus on scalability and performance [6][7]. User Session Management - User sessions begin when the Instagram app is opened, sending requests to a load balancer that distributes traffic to application servers [10][14]. - Initially, Instagram used two Nginx servers for load balancing, later upgrading to Amazon's Elastic Load Balancer for better reliability [15]. Data Storage and Management - Instagram utilized PostgreSQL for storing user and photo metadata, implementing sharding to manage the large volume of data generated by user activity [21][23]. - The photo storage solution involved Amazon S3 and CloudFront, enabling efficient distribution of images globally [28]. Caching and Performance Optimization - Redis was initially used for mapping photo IDs to user IDs, with optimizations reducing memory usage significantly [30]. - Memcached was employed for session caching, ensuring quick access to frequently used data [31]. Monitoring and Error Handling - Instagram implemented Sentry for real-time error monitoring and used Munin for tracking system metrics, allowing for proactive issue resolution [39][40]. - External service monitoring was managed through Pingdom, with PagerDuty handling event notifications [41]. Reflection on Market Timing - The article emphasizes that the founders' lack of experience with modern technologies and cloud services at the time hindered their ability to capitalize on the emerging market [43][46]. - It concludes that many opportunities may be missed due to a lack of insider knowledge and market readiness [49].