> ## Documentation Index > Fetch the complete documentation index at: https://docs.tied.com/llms.txt > Use this file to discover all available pages before exploring further. # Core concepts > The nouns every other page assumes you already know. Tied has about a dozen load-bearing nouns. Most of them mean roughly what you'd expect, but three or four carry precise meanings that matter — particularly when it comes to what you get billed for. This page reads as an argument; the [Glossary](/glossary) is the A-to-Z lookup. ## The container Everything else lives inside an account: inboxes, contacts, conversations, teams, agents, billing. Most companies need exactly one. You'd run more only to separate genuinely unrelated brands that should not share contacts or reporting. ## Where messages arrive The underlying medium — Apple Messages for Business, RCS, SMS, WhatsApp, email, web chat, Slack, Telegram and so on. A channel is the *how*: what the message travels over, what it can render, and what it costs to deliver. A channel plus its settings: which team owns it, how conversations are assigned, business hours, the greeting, the agent attached to it. **You connect channels, but you work in inboxes.** One channel type can back many inboxes — a support SMS number and a sales SMS number are two inboxes. This is the distinction people trip over most. "Turn on WhatsApp" is a channel decision. "Route WhatsApp to the EU team after 6pm" is an inbox decision. ## Who is talking One human, identified across channels. The same person texting you and later emailing you should resolve to one contact — which is what makes conversation history useful rather than fragmented. See [Contacts](/contacts). A thread of messages in one inbox. Carries a status — `open`, `pending`, `snoozed` or `resolved` — and a priority — `low`, `medium`, `high` or `urgent`. A contact can have many conversations, across many inboxes, over time. Typed as `incoming` from the customer, `outgoing` from your side, `template` for a pre-approved channel template, or `activity` for system events like an assignment change. Activity messages are what make a thread readable months later. ## Who handles it A person with access to the inbox. Confusingly, the industry calls both humans and bots "agents", so these docs always say **agent** for a person and **AI agent** for the software. The thing that reads the conversation, decides what to do, and does it. It can answer from your knowledge, read your connected systems, or write to them — bounded by the tool scope your plan grants. See [AI agents](/agents). Used for routing and reporting. Conversations get assigned to a team, then to a person within it. ## What the agent does A single call the agent made — a knowledge lookup, a read from your CRM, a write to your payment processor. Every action is recorded in a signed, immutable audit trail with what it touched and whether it succeeded. **This trail is not just logging.** It is what your resolution class is derived from, which is why the class on your invoice is provable rather than asserted. A chatbot flow built on the canvas — explicit branching for paths you want handled exactly the same way every time. Use a flow where determinism matters; let the agent handle the rest. See [Chatbot](/chatbot). ## What you pay for Not a closed conversation. Not a reply. A resolution is recorded only when a **positive signal** says the customer's problem is gone — they confirmed it, or one of your systems proved it, or they went quiet with a corroborator backing it up. **Most conversations do not produce one, and that is the point.** See [What counts as a resolution](/pricing/resolutions). Pegged at ten cents, fixed. Resolutions, channel usage and model cost all draw down the same balance. Everything customer-facing is quoted in dollars; credits are just the internal unit those dollars draw from. See [Credits](/pricing/credits). ## How they fit together The core objects: an account holds inboxes, an inbox holds conversations, and a conversation holds messages, with contacts and assignees attached. The core objects: an account holds inboxes, an inbox holds conversations, and a conversation holds messages, with contacts and assignees attached. These nouns in motion, from arrival to resolution. The order to create them in when starting from empty. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.