I was wondering why almost every other first-order-logic question refer to fitch style deduction? What is so different about fitch-style deduction that it has to be specified?
There is a software product from OpenProof Courseware called "Fitch" that goes with the Language, Proof and Logic textbook that appears to be what some people are referring to: https://ggweb.gradegrinder.net/support/manual/fitch Some of these questioners may be seeking help with this particular software product.
There is also a Fitch-style proof checker that I like to use that goes with the forall x textbook: http://proofs.openlogicproject.org/
However, the Fitch notation is an indented way to display subproofs in a natural deduction proof that was used by Frederic Brenton Fitch in his Symbolic Logic, 1952. Here is an illustration of the notation: https://en.wikipedia.org/wiki/Fitch_notation