tl;dr:"Internally, each Discord community is called a “guild”. A dedicated Elixir “guild process” handles coordination and routing for each guild. This tracks all connected users to the guild. Every online user has a separate Elixir "session process”. When the guild process gets a new message, event, or update, it fans out this information to the relevant session processes. These session processes then push the update over WebSocket to the Discord clients."
tl;dr:“We’ll arm ourselves with the knowledge necessary to make informed decisions when faced with the challenge of choosing databases for various components of our application. We will dive into the process of database selection, examining the various types of databases, discussing factors that influence database performance and cost, and guiding ourselves toward the best choices for our application while balancing essential tradeoffs.”
tl;dr:"Visa, Mastercard, and American Express act as card networks for clearing and settling funds. The card acquiring bank and the card issuing bank can be – and often are – different. If banks were to settle transactions one by one without an intermediary, each bank would have to settle the transactions with all the other banks. This is quite inefficient."