high availability
High availability is designing a system so it keeps running even when an individual part fails, by removing any single point that could take the whole thing down. For WordPress that usually means several web servers behind a load balancer, a replicated database, shared file storage every server can reach, and a central object cache, so losing one server doesn’t lose the site. A plain single-server install is the opposite: if that one server reboots or crashes, the site is down until it comes back. Enterprise hosts like WordPress VIP, WP Engine Enterprise, and Pantheon build high availability in by default, usually with uptime guarantees of 99.95 percent or better.
Also known as: HA, high availability architecture, failover, load balancing, HA hosting, redundant hosting
Where this term comes up
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Enterprise WordPress: the infrastructure decisions that cost teams later
“Enterprise” is a hosting upsell label. The four layers that actually matter (edge, application, data, observability) fit on one page. Here it is.
Glossary entries are a starting point. The real question is usually what to do about the thing once you understand it.
When you are ready to go further, the related guides take this from definition to fix.
And if you would rather just ask a person, I read everything that comes to christopher@thisismyurl.com.
I have been working in WordPress since 2007, so most of these terms come with a story.
Still mapping the basics? The full glossary is here whenever you need it.