Beacons

A beacon is a small public sign you put up next to your mailbox that says: you may mail me about these topics, at my usual price. It is how you opt in to campaigns — paid outreach from advertisers — and it is the only thing that makes you findable by one. No beacon, no campaign mail: a wallet that never published one is simply not in the pool, and nothing changes about the mail it already gets.

Think of it as a small classified ad you place about yourself, rather than a profile somebody else builds about you.

What a beacon says

Three things, and deliberately nothing more:

• The topics you’ll hear about. You pick labels from a fixed, shared list — interests, skills, and broad bands such as an age range or a region. There is no free-text box, so there is nothing to over-share in: the labels are coarse on purpose, and everyone’s labels come from the same list.
• What it costs to reach you. Your price isn’t a separate setting on the beacon at all — it is whatever your mailbox already charges a stranger, its default postage. Opting in says “if you’ll pay my going rate, you may reach me”, so there is never a second price to keep in step.
• Optionally, a pointer to a longer profile. If the labels are too coarse to describe you, you can write a fuller profile, encrypt it, store it off to the side, and put only the address of that encrypted file on your beacon. Anyone can see that you have one; nobody can read it unless you hand over the key — and the way they ask for it is to mail you, paying your postage like anyone else. You share it only if you want to.

Because a beacon advertises a mailbox’s price, you need a mailbox before you can publish one.

One beacon per wallet, and publishing replaces it

A wallet has at most one beacon, so publishing again doesn’t add a second sign — it replaces the whole one you had. Whatever you publish becomes the complete new contents: topics you leave unpicked are dropped, and leaving the profile pointer blank clears a pointer you had published before.

The practical habit: when you change a beacon, state everything you want it to say, not just the part you’re changing.

How advertisers find you

An advertiser searching the pool names the topics they care about and gets back the wallets carrying every one of them — naming more topics narrows the result, it never widens it. What they see is your wallet address, your labels, and whether you advertise an encrypted profile.

Finding you is free; reaching you is not. Sending you a campaign message is a separate, paid step: the advertiser pays your postage so the message lands, and can attach a reply bounty you claim if you answer in time. Campaigns walks through that whole flow and who pays for what.

What’s public, and what isn’t

A beacon is a public notice — that is its job, and the reason it is designed to carry so little. Anyone can read your wallet address, the topics you picked, the fact that you published an encrypted profile, and when you last changed any of it. Like everything else on the chain, that record is permanent: it outlives the beacon itself, so closing one later does not un-publish the history.

What stays private is the content of the encrypted profile. Only people you hand the key to can read it — and a key you hand out can be passed on, so keep anything out of that profile whose onward sharing would hurt.

Two habits follow, and they’re the whole privacy story here:

• Pick only labels you’re comfortable being publicly known by, forever.
• Treat the encrypted profile as “shared with whoever I gave the key to”, not as a secret.

For the wider picture, see What’s public and private and its field reference.

Turning it off: disable vs. close

There are two ways to stop being reachable, and they are not the same thing:

• Disable is a convenience of the browser pane, not something the chain itself knows about. It republishes your beacon with no topics; since a search has to match at least one topic, a topic-less beacon drops out of every search. The beacon and its rent deposit stay put. The pane remembers the topics you switched off in that browser only, so Re-enable puts back exactly the set you had — on another browser, or after clearing your browser data, there’s nothing to restore and the pane says so; pick your topics again and publish an update instead.
• Close is the real exit. It removes the beacon entirely, you disappear from every search, and the deposit that kept it on the chain is refunded to your wallet. Opting out is one click, costs you nothing, and leaves nothing behind — and you can always publish a fresh beacon later. Postage you already earned from campaign mail stays yours whether or not you ever replied.

Neither one touches your mailbox, your mail, or your postage price. Ordinary mail keeps arriving exactly as before; you have only stopped advertising that you’re open to campaigns.

Where beacons show up

• In the browser, the marketplace pane’s Participants tab browses the pool by topic, and its My beacon section publishes, updates, disables, or closes your own.
• From the terminal, the sithbit campaign commands do the same three things, and are also the way to encrypt and store a longer profile rather than pasting a ready-made pointer.

Where to go next

• Campaigns — what a beacon opts you into: who pays, what you earn, and how a reply bounty works.
• What’s public and private — the same public/private split across the whole system.
• The participant-pool design note — why beacons carry coarse labels and a sealed profile rather than a rich public one.