Romans used crucifixion as a form capital punishment from the third or fourth century B.C., until outlawed by Emperor Constantine in 347 A.D. Jesus certainly would have seen crucifixion growing up under Roman occupation.
Crucifixion was a typical form of execution for political insurgents. In Jesus' time and region, the crux commissa (tau cross) was used. A patibulum (the short section of the cross, estimated 70-80 lbs) was carried by the condemned person to the execution site. Arms were typically fastened to the patibulum with nails, which was then lifted and placed on the stipes (the long section of the cross, permanently fixed in the ground), held in place by a mortise and tenon joint. Feet were then fastened to the stipes with nails.
Crucifixion was a feared, protracted means of execution, marked by pain, likely infection, exhaustion, and environmental exposure. The torture of crucifixion could last for several days before the victim finally expired.
The titulus crucis, a plaque stating the crimes for which the condemned was being executed, was fastened to the cross for public view. For Jesus, the statement was "Jesus of Nazareth, King of the Jews" (John 19:19).