a generl PPC question...

I'm thinking of doing the PPC service in google or yahoo. I would like to know if it's possible to "spend" me ad.
What I mean by that I don't know if a competitor of mine can see my ad and just keep click on it untill it's gone
and in that way my money went for nothing. Is it working like that?

It depends on the competitor. Click Fraud is a big problem. But it doesn't effect everyone or every industry.

I wouldn't let it stop you from doing PPC. Just keep good records and watch your comaigns for any abnormal clicking. If you have an average of 100 clicks per day and then out the blue 3 days in a row you have 1000 with no increase in coversion... then you might have a prob.

Good Luck!

How can I take care of the problem in case I found out?
Does google or yahoo remember the user that click on the link and won't count the click in case there's more then one click from this user/IP?

IMO google has a fair handle on this. If someone was going to click you to death they would have to go to a lot of effort to do it from or make it look like it was coming from a wide range of IPs.

I am sure that click fraud is a problem - but widely distributed instead of attacks on YOUR advertising budget. Will you lose some to fraud? Probably you will and especially if you send your ads out to adsense sites.

But if you don't start because of this worry you will have deprived yourself of an important opportunity.

Thank you guys!