Pagefile (pagefile.sys)
Also known as: page file, virtual memory Windows, pagefile.sys
The pagefile (pagefile.sys) is a hidden Windows system file used as virtual memory — overflow space on disk when physical RAM fills up. It is managed by Windows, often several gigabytes, and should not be deleted, since removing it can hurt stability and performance.
- Acts as virtual memory when RAM fills
- Managed by Windows; do not delete it
- Configured under Virtual memory settings
What the pagefile does
When running programs need more memory than the installed RAM provides, Windows moves less-active data to pagefile.sys at the root of the system drive. This virtual memory keeps the system stable under load, at the cost of disk space and slower access than real RAM.
Its size scales roughly with your RAM and workload. On a drive with limited space it can look like a large mystery file, but it is doing necessary work.
Should you touch it?
In almost all cases, leave it on automatic. You can review or resize it under Settings > System > About > Advanced system settings > Performance > Settings > Advanced > Virtual memory, but disabling it can cause apps to crash when memory runs low. Shrinking it to reclaim space is rarely worth the risk.