Operational Expenditure - ongoing costs for services you use and pay for regularly, like cloud subscriptions. Like renting an apartment with monthly payments.
Cloud computing shifts IT spending from CapEx to OpEx, where companies pay monthly for the cloud resources they actually use instead of buying expensive hardware upfront.
OpEx (operational expenditure) is an accounting/finance concept, not a cloud service. All major cloud providers primarily bill usage as ongoing operating costs (OpEx), such as monthly invoices for compute, storage, and managed services.