I have to disagree with the previous posting.(posted 7994 days ago)Without prejudice means that the party which wants to negotiate a settlement can do so 'without prejudice' so that they are not embarassed by any admission that they need to make to try and broker a deal during the course of negotiations.
The idea is to get people to settle their differences out of court rather than fight in court. It also excludes details of any settlement negotiations from being disclosed in court.
I have seen a solicitor write a 'without prejudice' letter trying to broker a deal, but reserving the right to produce that letter in court if I refused to accept their offer. In this matter, I was very confident that I was going to win and refused to negotiate - that letter was never produced in court as the other solicitor knew his client hadn't a leg to stand on.
WP can get a bit more complicated, but this is the general idea. Hope this helps.
Pendle