sentences:  Most policy decisions are left to VCL code, making Varnish more configurable and adaptable than most other HTTP accelerators.When a VCL script is loaded, it is translated to C, compiled to a shared object by the system compiler, and loaded directly into the accelerator which can thus be reconfigured without a restart.A number of run-time parameters control things such as the maximum and the minimum number of worker threads, various timeouts, etc.