I have a pinching in my sciatic nerve. Was told about the surgery called decompressive laminectomy. What is that?

First most are . Treated non op including giving it time to heal, Physical therapy, meds like non steroidal anti inflammatories if no reason not to use, epidural steroid injections and if no better then surgery if CT or MRI reveal a pinching or compression of nerve due to disc herniation or bony narrowing (stenosis) or both treated by removing part of roof of spine (lamina- laminectomy) decompressing nerve.