Cancelled flights: will planes remain grounded?
Frontier Airlines has grounded flights for more than two hours, blaming problems with Microsoft's online services.
In the US, American Airlines, United and Delta have asked the Federal Aviation Administration to impose a global halt on all flights, according to an alert from the FAA.
Ryanair has asked passengers to arrive for flights an hour earlier than normal and Manchester Airport has said its ground crews are carrying out the work manually.
All flights have reportedly been grounded at Berlin Brandenburg Airport after the airport initially warned that a technical issue would cause delays at check-in.
IndiGo, the low-cost Indian airline, has said it is experiencing an ongoing issue with Microsoft Azure. The company said customers may have difficulty obtaining boarding passes and some flights may also be affected.
Gatwick Airport said it was relying on backup processes to process passengers this morning but had kept its terminals open. "This is a global Microsoft issue affecting some airlines' check-in, baggage and security systems, including eGates," it said.
Photos have been posted of large crowds of people gathering at Brussels' Charleroi airport due to severe delays.
Dutch airline KLM has said it will suspend most of its operations after warnings that flight handling has become "impossible" due to problems.
Amadeus, a company that handles baggage at Heathrow, has now confirmed it has been affected.
Photos have now surfaced of airports in Europe where travellers are kept informed about their flight using whiteboards and markers.
Are there trains running today?
Thameslink, Southern Rail and Gatwick Express are experiencing "widespread IT issues across our network" which means they are unable to access driver diagrams at some locations. They say this will lead to potential delays, particularly on Thameslink and Great Northern. There are also reports of ticket machines not working at some stations.
Northern rail operator Merseyrail has warned that the crisis is affecting passenger information boards and the ability to print third-party tickets at stations.
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Metro services in the US capital have been affected. Operator Metro Forward has said its internal systems are down. Its website was inaccessible at the time of writing.
Back in London, staff have been deployed to manually scan tickets at Waterloo.
Bookmakers
Even high street bookmakers aren't immune to the outage, it seems. Ladbrokes told customers trying to access its site this morning that it was "experiencing some technical difficulties". Outage tracking website Downdetector reported a surge in complaints from users trying to access the bookmaker today.
Sports, museums and entertainment
Manchester United have postponed their planned ticket rollout for today. The Matchday X account said it hoped to launch tickets in the afternoon, as it warned of ongoing issues with its website. Middlesbrough FC have also said they are unable to process card payments.
It looks like many cultural institutions across the country will struggle to accept card payments today. A host of museums, visitor centres and cultural venues, from Portsmouth's Historic Dock to Glasgow's Science Centre and Monkey World in Dorset, have warned that visitors will have to pay in cash.
News organizations
Sky News stopped broadcasting and ran a message apologising to viewers this morning, but has since resumed broadcasting.
The Telegraph is experiencing problems logging into computer systems and accessing the internet.
CBBC is down. A blue screen is currently telling viewers "Sorry! Something went wrong". The service has now resumed.
Banks and financial institutions
The London Stock Exchange (LSE) has warned that its data feed is currently experiencing technical issues, meaning the company's results and announcements are being delayed. It said: "The RNS news service is currently experiencing a third party global technical issue which is preventing news from being published on londonstockexchange.com."
Leading banks across Australia have been hit, with the Commonwealth Bank saying it is "urgently investigating any impact on our systems and services" after some customers were unable to make payments.
In New Zealand, banks ASB and Kiwibank have announced that their services are unavailable.
There are photos available indicating that exchange rates in Hong Kong have been disrupted.
Emergency services
The NHS has highlighted issues with its EMIS appointment and registration system, but stressed that steps have been taken to address problems, such as paper patient records and handwritten prescriptions.
911 outages have been reported in several US states, reportedly including Alaska, New York City, Arizona, Indiana, Minnesota, New Hampshire and Ohio.
There are also unconfirmed reports of failures in electronic medical records (EMR) systems in U.S. hospitals. These systems are used by doctors to store and organize patient information.
Israeli systems have also been affected, with the country's Health Ministry warning that the cyber outage is causing hospital services to stop working, Haaretz reports. Social media posts indicate that some hospitals in Israel have switched to manual systems, while citizens have been warned that they may have difficulty reaching emergency services by phone.
healthcare
GP services across the UK are reporting issues causing major disruption to practices, with some losing access to medical appointments, medical records, booked appointments and even prescriptions, according to posts on social media from practices.
Schools and universities
The education sector has not escaped unscathed. A number of institutions have now told children to stay home on what would have been their last day of school for the year. Some parents have been told to call if their child is ill because the school's IT systems are down. The University of Manchester has said it is investigating IT issues "as a matter of urgency".
Supermarkets
Even some self-checkout areas in supermarkets have been affected by the outage, social media users report. For example, photos of checkouts at Australian supermarket Woolworths with the so-called 'Blue Screen of Death' on X have been posted.
British supermarkets also appear to have been affected. Some Morrisons customers reportedly struggled to use contactless payments this morning, while customers have complained they were unable to pay in Waitrose stores. Sainsbury's said it had not seen any issues with its own systems.
Downdetector is reporting a flood of consumer complaints about Waitrose, Tesco, Morrisons and Sainsbury's. However, the supermarkets visited by Telegraph journalists this morning appeared to be operating normally.
Pubs and catering
Pub chain JD Wetherspoon has confirmed that there are issues with its app, which customers use to order food and drink at their table. The chain has advised that customers should pay for their food and drink with cash.
Reports have emerged that coffee chain Gail's is no longer accepting card payments as a result of the outage.
