When I first started building sites there were many people that said you shouldn’t link your websites together, and if you do then do it with caution.

Back in the day spammers would love linking tons of sites together.

As time went on some blog networks were showing up and linking dozens of sites together without much ill effect.

I’ve successfully made my own little network of up to 15 sites and it didn’t seem to hurt anything.

However I still wonder, will linking my sites together ever hurt me in the search engines? Will google flag me as a spammer? And if yes, at what point?

What’s the current opinion on whether or not to link your sites together?