This has been shared in the comments section but things easily disappear over time.

This is a very, very, long explanation and is best suited hosted elsewhere.

Read: (Updated) 《Grid (그리드)》 Explained

These are some of the questions answered:

• Did Sae Ha die?
• What is the relation of Sae Ha's death to the Ghost and the Grid?
• Who is the Storehouse Sae Ha?
• Is Kim Ma Nok the ancestor of the Ghost?
• Why did the Ghost appear in various labs around the world?
• Who is the Blue Time Traveler?
• How come Eo Jin said it was Sae Byeok who told him the name of her daughter?
• If there is no Grid in the Ghost's time, should she not exist at all?

And many more.

The article was written by establishing a common ground first. In each question, the MDL member who asked it was credited.

Read: (Updated) 《Grid (그리드)》 Explained

Enjoy!

(Feel free to leave comments here, in this MDL thread, or on my blog.)