Net etiquette regarding links

[Evening Star]

Suspect this may count as a dumb question, have done a Google and cannot find an answer, so here goes anyway. Currently finishing off writing my first website and need to know if it is polite to inform a website owner if my website is linking to it? Or I am being over worried concerning politeness by thinking such a thing?

[5711N0205W]

A short answer, yes it is polite, if your site and the site you are linking to are in a similar subject area then you may like to ask the other site to link back to you, this can improve your search engine standing.