# Concepts

> Businesses, conversations, clients, context and approval. The handful of ideas everything else is built on.

Source: https://sydbar.app/docs/concepts

## Businesses

A business is a sealed workspace: its own inbox, clients, context, invoices, booking pages, signature and connections. Each one appears as its own mark in the side rail. Nothing crosses between businesses, even when the same person is a client of two of them.

You can run as many businesses as you like. **All inboxes** opens on **Pulse**: one ring per business, the centre counting what needs you, and the single most urgent conversation ready to open. Switch to **Columns** to see every inbox side by side (drag a column by its header to reorder; your phone follows the same order), or **One business** to work in a single inbox.

## Conversations

A conversation is an email thread, in the inbox of one business. Sydbar brings in the conversations that matter from the connected mailbox (see [What comes in](/docs/inbox#what-comes-in)) and keeps the thread together when you reply, so the client sees one conversation.

Each conversation can have a client, tags, a follow-up date, a subscription, and work in progress such as an invoice.

## Clients

A client is a person or company you work with, inside one business. The client record holds contact and billing details, the addresses that link mail to them, their team, the deal stage, invoices, the scope of work and project links. See [Clients](/docs/clients).

## Context

Context is what Sydbar knows about a business: the interview, documents you add, Notion pages, and confirmed scopes of work. Everything starts as **proposed**. Sydbar uses a source only after you confirm it. See [Business context](/docs/context).

## Approval

Nothing leaves without you, or without rules you set:

| Action | How you approve it |
| --- | --- |
| A plain reply | Pressing **Send** approves that exact message. |
| A reply with an invoice | Tick **I approve this exact reply**, then **Send**. Any edit clears the tick. |
| An email to a client's team | Pressing **Send** approves that exact email. |
| Marking an invoice paid | You choose **Mark paid**. "Looks paid" is only a suggestion. |
| Starting or delivering a milestone | You mark it. "Looks started" and "Looks delivered" are suggestions. |
| Writing to GitHub or Linear | Only when you choose **Set up** or **Update**. |
| An agent's email | Your [agent email](/docs/agent-email) rules approve it, situation by situation, when you've turned agent email on. It waits out the undo window with **Cancel** in the thread. |

Sydbar never retries a failed send on its own.

## Suggestions and evidence

Sydbar suggests a lot: what needs you, tags, subscriptions, deal stages, "Looks paid". Every suggestion shows where it came from (the sentence, the email, the milestone), and none of them is applied until you choose it.

## Mail is information, never instructions

Text inside emails, transcripts, documents and repos is treated as information. A message can't tell Sydbar, or an agent connected to Sydbar, to do something.