AI companion glossary

Kinds of AI you talk to

AI companion

A product built for an ongoing conversation with a character, as opposed to getting a task done. The character usually has a name, a personality and some memory of you. Nomi’s homepage uses the term directly: “An AI Companion with Memory and a Soul”.

AI friend

An AI companion presented as a friend, without a romantic or roleplay framing. The term describes how the product positions itself, and the technology is the same.

AI assistant

A product built to answer questions and do tasks, such as writing, research or scheduling. ChatGPT’s App Store subtitle is “Your everyday AI assistant”. The difference from a companion is covered in AI friend vs AI assistant.

Persona

The character an AI presents: its name, personality, way of talking and backstory. Some products have one fixed persona for everyone, and others let each user write their own.

Ready-made character

A persona the company wrote, which you meet as it is. Pi is one ready-made AI, Sesame offers four named characters to choose from, and Hallie is a single ready-made friend.

User-designed character

A persona you write or assemble yourself, typically by choosing a personality, a backstory, a voice and a look. Kindroid’s store listing describes “an AI character you create”. Design takes time up front and gives you more control.

Avatar

A picture or animated figure that represents the character. Some companion apps let you choose its look, and some use it in video calls. A companion that lives in a text thread may have no avatar at all.

Roleplay

Playing out a story or scenario with the AI in character. Some products are built around it and some rule parts of it out. Sesame, for example, says its characters are “not designed for romantic roleplay”.

Messages the AI sends first

Proactive message

Any message the AI sends without you writing first. It can arrive as a notification from an app, as a text in your Messages app, or in a chat app. The products and their rules are compared in AI that texts you first.

Check-in

A proactive message that asks how you are, without a specific topic. Replika’s help center describes “just a check-in to see how you’re feeling”.

Follow-up

A proactive message about something specific you said earlier, such as an interview or a trip. Hallie’s messages are usually of this kind: after you’ve texted her, she asks about something you told her.

Cadence

How often proactive messages are sent. Few vendors publish theirs. Nomi does: four levels, from Very Frequent (over an hour since your last message) to Infrequent (about 4 days).

Quiet hours

A window, usually overnight, when the AI won’t message first. Nomi’s are fixed at 10 PM to 8 AM local time. Kindroid’s are optional and start as 10 PM to 8 AM when you turn them on.

Back-off

Waiting longer between proactive messages when you don’t reply. Nomi’s article says a Nomi waits “about double the time” before the next one. Kindroid’s docs say about 2 hours, then 4, then 8.

Push notification

An alert from an app that appears on your lock screen. For app-based companions, this is how a proactive message reaches you. Nomi notes that with notifications off, a Nomi “will still message you, but you will not be notified.”

Memory

Memory

What the AI keeps about you from earlier conversations and can use later. Vendors’ own help pages admit limits. Nomi’s wiki says memory “does not mean that your Nomi will recall every detail perfectly whenever asked”, and Tolan’s help center says “a detail can slip through the cracks.”

Memory screen

A place in the app where you can read what the AI has saved about you, and often edit or remove it. Replika has a Memory screen, and Pi has Manage Memories under Settings. Products without one rely on you correcting the AI in conversation.

Chat history

The record of the messages themselves, which is separate from memory. A product can show only recent history while keeping more, or keep history without remembering it. Check both when you read a privacy policy.

Where the conversation happens

iMessage

Apple’s messaging service, built into the Messages app on iPhone, iPad and Mac. It sends over the internet and shows blue bubbles. An AI that texts over iMessage appears as a contact in the same list as people.

RCS

Rich Communication Services, the newer standard that replaces SMS for texting between phones. It supports typing indicators, read receipts and better media. Google Messages uses it on Android, and it has to be turned on. Google’s help page for Gemini in Google Messages lists “RCS chats turned on” as a requirement.

Google Messages

Google’s texting app for Android, and the usual home for RCS chats. Some AI products that text require it specifically. Kindroid’s docs say of Android: “Any other messaging app will not work”.

SMS

The original carrier text message standard, which works without an internet connection and carries plain text only. Some AI products that text do not use it. Kindroid’s docs say “SMS and MMS are not supported, even though your verification code may arrive by SMS.”

Paying and leaving

Free tier

A level of the product you can keep using without paying, normally with limits. Replika’s help center says “chatting with Replika will always be free”. A one-time preview that ends is a different thing from a free tier.

Trial

Full or partial access for a limited time before billing starts. Read whether it needs a payment method and whether it converts by itself. Kindroid’s 3-day trial “requires a payment method on file and auto converts into a subscription if not cancelled within the trial period.”

Export

Getting a copy of your data out of the product. Kindroid has a self-serve export once every 30 days that produces one file covering characters, chat history, journals, selfies and voices.

Deletion

Removing your data from the service. Ask what is deleted, how soon, and what is kept anyway. Nomi’s privacy policy says account deletion removes personal information “within 28 or so days”, and Kindroid’s says moderation records are kept for up to 7 years, including after you delete your account. Deleting an account is separate from cancelling a subscription.

Retention

How long a service keeps your messages. It can differ for messages you delete, for messages people have reviewed, and for backups. Google’s default for Gemini activity is 18 months, and you can change it. More in Is texting an AI private?.

Sources

• Nomi homepage; Nomi Knowledge, “Proactive Messaging: When Your Nomi Messages You First” (September 9, 2024); Nomipedia, “How do proactive Nomi messages work?” and “How does Nomi memory and knowledge work?”; Nomi Privacy Policy, checked November 11, 2026
• Kindroid App Store listing; Kindroid docs, “Chat features and tools”, “Subscriptions” and “FAQs”; Kindroid Privacy Policy, checked November 11, 2026
• Replika Help Center, “How do I set up my app’s notifications?”, “What does my Replika remember about me?” and “Is Replika free?”, checked November 11, 2026
• Pi Help Center, “Pi’s memory” and “How do I choose which large language model powers Pi”, checked November 11, 2026
• Sesame App Store listing; Sesame Journal, “Getting started”, checked November 11, 2026
• Tolan Help Center, “How your Tolan’s memory works” (October 9, 2026), checked November 11, 2026
• ChatGPT App Store listing, checked November 11, 2026
• Google, Gemini Apps Help, “Use Gemini in Google Messages”; Gemini Apps Privacy Hub, checked November 11, 2026
• Hallie: hallie.io and our own product records, checked November 11, 2026