Due to the advancement in technology, these days, writers are able to create a lot of fantasy in their writing.  This is done through world building which is a lot more than just a framing device.  World building is the very essence of any science fiction or good fantasy.  In addition to this, it is the base of a sense of place in the other genres.  When you use the appropriate world building, it lends an immense richness to the writing.  It also gives your readers the details they require to understand plot lines and characters.   This article gives an insight of world building guide to help writers create a fantasy in their writing.

To start with, writers can be able to build worlds in their fiction by breaking down the world building concept into three main categories.  The first category involves imaginary worlds whereby the construction of all fictional universes is found primarily in fantasy genres.  The second category is through alternate reality where writers use imaginations of the existing world.  In the third category, writers normally use actual locations where a real place in the world is utilized without any element of fantasy.

When it comes to the use of the imaginary world, writers usually face the most complex kind of world building.  This is because this category is often utilized in science fiction and fantasy.  The writer is required to conjure up every detail from scratch which involves history, geography, language, characters, politics, etc.  Thus, it is quite overwhelming for writers to create all these elements in order to form a whole fictional world. Read more info here.

On the other hand, the alternate reality category is almost similar to creating an imaginary world.  However, since the writer uses the existing base that they have to work with, it becomes slightly demanding than the imaginary world category.  Hence, a writer is required to develop an alternate version of their own world and has to imagine how things would be different.  They also pose questions on these differences and what they would mean for humanity.  This kind of writing is therefore good for expressing thoughts about today's world and the flaws of humanity.

The final category of actual locations is also used by many writers to express their fantasy.  Place has an essential role in every story, and therefore it is often used to create a big effect in literary fiction.  In novels that have a strong sense of place, their setting fundamentally becomes a character in itself.

See more here: https://en.wikipedia.org/wiki/Worldbuilding.