This inhibits the production of esters and results in a clearer tasting product. These are classic beers ales, lagers etc. The fruit should b pasteurized by placing it in the primary and pouring 150 degree water over it. Use this water as part of your liquid. Add the cooled wort to the fruit and proceed as usual.
Some brewers prefer to add the fruit to the secondary and that's fine.
The flavor is probably stronger, but I hate trying to clean the carboy afterwards. If you choose to put it in the secondary you need to go Ahead and pasteurize it. And you will need to clear it further with a third or tertiary fermentation 2-3 days should do it.