Global blocks are technical measures employed against IP addresses to prevent them from doing certain actions.
Global blocks are technical measures that Stewards, Global Sysops, and Trust and Safety can use to prevent IP addresses or ranges from doing certain actions such as creating user accounts, editing, and editing their talk page. In some rare cases, these blocks may be applied so that they also affect users who are logged in thus preventing users in certain blocked ranges from editing as if they too were blocked. Global blocks differ from global locks which can only be applied to registered user accounts and which can't have an expiration specified. Global blocks can either be temporary or permanent though it is rare for them to be permanent. All global blocks are logged here on Miraheze Meta at Special:Log/gblblock.
Global blocks are usually placed to prevent IP addresses or ranges from editing but can be extended to include preventing account creations or editing of user talk pages. Global blocks are usually applied to disruptive, cross-wiki vandalizing IP ranges or IP addresses/ranges found to be violating the No open proxies policy.
To request a global block, please use the Stewards' noticeboard. In cases of cross-wiki vandalism, spam or other disruptions, you can also report any problematic IPs on the Counter Vandalism Team's IRC or Discord channel to have either a Global Sysop or Steward block the address or range either locally or globally.
If you happen to be affected by a hard block (blocks which prevent account creation or which also affect users who are logged in), please email cvtmiraheze.org to request they make an account for you or exempt you from the ban. Note that global blocks typically do not affect logged-in users except in some rare cases.