Writing online is different. It is far more different from writing offline (for print or other media).
This difference is mostly because of the short attention span of people while they are online. Plus the many amounts of distractions they can encounter online.
Imagine you buy a book and start reading it. Let’s say you take the book with you to bed every day and read it for 30 minutes.
Depending upon the size of the book, you would finish reading it in a week or in a month.
But while you’re reading the book for 30 minutes every day, you’ll only read the book.
You won’t pop into Facebook to check on your friend’s updates, you will not check this-one-email of yours, you won’t be responding to 4 chat messages from 4 of your different friends and so on.