Does X (Twitter) notify someone when you follow them?

X tells people about a new follower in up to three places, depending on their settings:

• Their Notifications tab. X's help on the Notifications timeline says it shows "your new List followers, as well as your new account followers", and that "All shows you notifications for account activity like new followers, Reposts, mentions, and likes."
• A push notification on their phone, if they've turned on "New followers". It's one of the types in X's push settings: Settings and privacy, then Notifications, then Preferences, then Push notifications. X doesn't say whether it's on by default.
• An email. X's following FAQ says: "By default, X sends you an email to let you know when someone new follows you."

The email isn't one per follow anymore. X's page on email preferences says: "As of June 2017, X now sends a digest email referencing all your unread notifications about activity related to your account, instead of separate emails for each type and instance." It also warns that if you turn on emails for follows, "you may not receive a notification for every Repost, reply or mention, like, or follow."

We couldn't find the wording of these alerts in X's help or in its web app's text. So we can't quote what the person reads, only where they read it.

The unfollow itself sends nothing. X's following FAQ says: "X does not send a notification when you unfollow someone."

X's help doesn't say that unfollowing takes back the follow alert. Its page on following issues even describes alerts about followers who later left: "If you received a notification from X alerting you to a new follower, but don't see that person later in your followers list, it's likely that account was hidden for spam activity, unfollowed you, or deactivated their account." X can't pull an email back out of their inbox, and its help describes no way to recall a push notification. X doesn't say whether the entry in the Notifications tab disappears.

If their account is protected, Follow sends a request instead. If you cancel it, X's app says the person "will no longer see it". But X's help on follow requests says they may have had "an email notifying you of a new follower pending approval" already, and that a request missing from the list was probably cancelled. More on requests in how to make your X account private.

What an unfollow tracker sees is another matter: does X notify when you unfollow?

Push and email alerts, yes, and only the person being followed can. Push alerts for "New followers" are a switch in their push settings. Follows are also one of X's email types ("if you are followed by someone new"), and the digest has its own switch, which X's help calls "Email me when I have new notifications". X adds that you get the digest "if your settings were enabled to receive all individual activity email notification types."

Whether X's notification filters hide a follow, X doesn't say. Its quality filter removes "lower-quality content" such as "duplicate posts or content that appears to be automated", and spares "people you follow or accounts you've recently interacted with", which a new follower often isn't. Its advanced filters turn off notifications from six kinds of accounts, all of them accounts "you don't follow", such as new accounts or ones with a default profile photo. The quality filter can also hide accounts from your followers list: why X doesn't show all your followers.

All of these settings belong to the person being followed. X's help describes no way to follow someone without the alert.

Not in anything X's help lists today. The Notifications timeline page names likes, Reposts, replies, mentions, new List followers and new followers of your own, and nothing about the accounts that people you follow have followed. It only adds that X will "elevate content that we think you'll be most interested in".

Twitter has shown such follows before, though. From 2011 an Activity tab showed which accounts the people you follow followed, until Twitter retired it from its iOS and Android apps in 2015. In July 2017 the Notifications tab started showing some of them. X doesn't say whether it still does. And anyone signed in to X can open your Following list while your account is public. If it's protected, X doesn't say who can: see who someone recently followed.

Post notifications don't help here. X describes them as a setting for "accounts you follow whose posts or live videos you don't want to miss", so you need to follow first. X's app says that with them on, "you'll know when they post, go Live, and host a Space." No X page says the account is told that you turned them on.

Without a follow, you can open a public account's profile when you want to, or add it to a private List. X says "Only you can view your private lists". Whether a public List addition notifies anyone today, X's help doesn't say: which X Lists are you on?

The sources are TechCrunch in May 2009, July 2010 and July 2017, Twitter's blog in November 2010, April 2012 and August 2016, Twitter's email help as archived in June 2017 and July 2017, and @Twitter's post, since deleted: "Just got a new follower? Starting today, we'll show their profile in your notifications."

We don't follow anyone for you, and we don't DM anyone about a first follow. Your dashboard counts your new followers and lets you see them all, so if the person you follow uses UnfollowMonkey, you show up on theirs after their next check. Our DMs are mostly about the other direction, the one X stays quiet about: when someone unfollows you, we DM you their name at the next check, once a month on Free and every day on the paid Kong plan.

If someone unfollows you and follows you again within 40 days, the next check reports that they "followed you again", in a DM and on your dashboard. So if you unfollow one of our users and follow them again soon after, our DM can tell them. A follow that lasts a few minutes usually falls between two checks, so we don't see it at all.