tl;dr on the global online outage:

the developers of crowdstrike, an ‘‘anti-ddos’’/endpoint protection software, released an update that broke a critical component, csagent, which operates within the windows kernel. this caused systems protected by it to fail a bugcheck, resulting in boot loops and BSODs on all windows devices which recieved the update

this major error by the software developers led to widespread chaos, disrupting a lot of online services globally, such as european and american airlines, hospitals, and many other important online services