What you need to know

• Global outages: Tech disruptions worldwide have hit airlines, banks and businesses, which are scrambling to respond.

• What’s behind this? The outages appear to stem at least partly from a software update for Microsoft Windows operating systems issued by cybersecurity firm CrowdStrike, experts tell CNN.

• Fix deployed, but impacts remain: CrowdStrike’s CEO said that a fix has been deployed. And Microsoft said the “underlying cause” has been fixed, but that the outages are still affecting some services.

• Travel stalled: Major US carriers including Delta, United and American Airlines have had flights grounded by authorities. Airlines in Europe and Asia-Pacific region have also seen disruptions.

• Critical infrastructure hit: Banks in Australia, New Zealand, South Africa and Britain have been affected, while Israel’s hospitals are facing a computer “malfunction,” and the UK’s National Health Service said most GP practices in England had been affected.