of downtime). The downtime was particularly noticeable during events popular with the technology industry such as the 2008 Macworld Conference & Expo keynote address. On January 12, 2023, several third-party Twitter apps (Tweetbot, Echofon, and Twitterrific) stopped working in various ways, leaving developers – and their many users – in the dark about the status of third-party app support. User accounts Verified accounts In June 2009, after being criticized by Kanye West and sued by Tony La Russa over unauthorized accounts run by impersonators, the company launched their "Verified Accounts" program. Twitter stated that an account with a "blue tick" verification badge indicates "we've been in contact with the person or entity the account is representing and verified that it is approved". In July 2016, Twitter announced a public application process to grant verified status to an account "if it is determined to be of public interest" and that verification "does not imply an endorsement". Verified status allows access to some features unavailable to other users, such as only seeing mentions from other verified accounts. In November 2020, Twitter announced a relaunch of its verification system in 2021. According to the new policy, Twitter verifies six different types of accounts; for three of them (companies, brands, and influential individuals like activists), the existence of a Wikipedia page will be one criterion for showing that the account has "Off Twitter Notability". Twitter states that it will re-open public verification applications at some point in "early 2021". In October 2022, after the takeover of Twitter by Elon Musk, it was reported that verification would instead be included in the paid Twitter Blue service, and that existing verified accounts would lose their status if they do not subscribe. On November 1, Musk confirmed that verification would be included in Blue in the future, dismissing the existing verification system as a "lords & peasants system". Following concerns over the possibility of impersonation, Twitter subsequently reimplemented a second "Official" marker, consisting of a grey tick and "Official" text displayed under the username, for high-profile accounts of "government and commercial entities". Privacy Tweets are public, but users can also send private "direct messages". Information about who has chosen to follow an account and who a user has chosen to follow is also public, though accounts can be changed to "protected" which limits this information (and all tweets) to approved followers. Twitter collects personally identifiable information about