What is pre-cum?

Pre-cum is a liquid with a similar consistency to semen that seeps from the tip of the penis during sexual excitement before ejaculation happens. The purpose of this is to lubracate the urethra before the ejaculate is discharged.

yup, Afarewell is right,

it is a sticky liquid which is ment to lubricate the tip of the penis prior to penetraction to make intercourse easier it also serves to neuralize any traces of urin as the acid in the urin is deadly to sperm cells. normally pre-cum does not contain sperm cells but it is possible so people can get pregnate from precum although it is not very likley