Male sterilisation, the snip
A vasectomy operation involves the cutting or sealing of the vas deferens which carries sperm from the testes to the penis. Thus the semen which is produced at ejaculation is normal but does not contain any sperm. It is a minor surgical procedure which can be carried out under a local anaesthetic, and takes about 10 minutes to perform.
It is possible to have a vasectomy reversal, but you should bear in mind that the success rate is less than 50%.