Useful websites for Path of Exile:

https://pathofexile.gamepedia.com/Path_of_Exile_Wiki (Use the search function, stop bothering others when you can find the answer yourself, plus you get the good answer...)

https://www.pathofexile.com/forum/view-thread/549432 (full beginner's guide, may not be up to date completely but a lot of information in there is still viable)

https://github.com/Openarl/PathOfBuilding/releases (A MUST HAVE, let's you create and simulate your builds, its insanely usefull)

http://poe.trade/ (for trades)

http://currency.poe.trade/ (for currency trades)

http://poe.ninja/ (nice updated list of items with their value, in different leagues)

http://poeaffix.net/ (to understand mods on an item)

https://siveran.github.io/calc.html (to figure out which method is the most efficient to get the colors you want on your sockets)

https://poe.mikelat.com/ (nice tool to calculate if u can fit said auras in your mana pool)

https://www.pathofexile.com/forum/view-thread/1246208 (link to a decent lootfilter, all the explanations for the installation is in there)