This site was created to help players sort through the massive amount of information for Factorio. There are numerous tutorials, and even more let's plays out there, and it can be hard to find exactly what you might be looking for.
The site is broken down into several areas. Guides and Tutorials make up one section, which is split into two sub-sections of Videos and Written Material. There is a Let's Play section that lists many different Let's Plays for Factorio, both old and new. There is also a Game Reviews section that is a collection of all the major reviews of the game. It is also planned to have a section for Builds and Designs in the near future.
Originally written by Xterminator, the official Factorio Manual/Guide covers all the major concepts in the game. It contains many screenshots from the game and links to outside sources (like YouTube videos, forum posts, etc) to help further explain each topic.
The manual is aimed at Beginner and Intermediate players primarily.
The guide covers many different topics in mostly chronological order. Some of the main things it goes over are Transport Belt and Inserter mechanics, Pollution, Science, Logistics System, Enemies & Combat, and much more. It also includes a full item index that lists every item in the game with a picture and short explanation.
Artwork done by the talented Dibujor over at www.dibujor.com
Factorio Mod Spotlights is a collection of videos previously done by Fishsandwich and Xterminator, and now solely done my Xterminator that goes over new (and sometimes older) mods. A new video is released each week on Wednesdays and so far there are 75+ videos between the two channels with each one covering a different mod.
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Factoratio is a great tool to help figure out ratios and material/time requirements for making something from start to finish. You input the item you want to make, and how many you want to make per minute, second, or hour and it will tell you exactly how many materials you need for each step and how many assemblers you'll need, etc (as you can see in the picture above).
It also has several other features, like showing the cost of all the technologies, and finding specific items and then seeing everything they are used for and what materials they require to make. Highly recommend checking it out if you like pre-planning your factory at all.