added a bit more information...

data/public.md

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 ## What is SWIFT?
 
+SWIFT is a Smoothed Particle Hydrodynamics code for Astrophysics. What does
+that even mean? It is a computer program designed for running on supercomputers
+that simulates forces upon particles due to two main things: gravity and 
+hydrodynamics (forces that arise from fluids rubbing against each other).
+This turns out to be quite a complicated problem, partly because we can't build
+computers large enough to simulate down to an atomic level, so we need to
+re-think the equations that describe the particles and how they interact,
+and partly because we must solve the equations that describe these problems
+numerically.
+
+We use SWIFT to run simulations of Astrophysical objects, such as galaxies.
+We do this to test theories about how the Universe came about and evolved from
+the big bang up to the present day!
+
+< MOVIE >
+
+
 + SPH Code
 + Used for Astrophysics
 + Calculates gravity + forces due to fluid dynamics
 
 ## Why create SWIFT?
 
-+ We want to simulate the Universe!
-+ Eagle II?
-+ Old codes were slow
-+ They had a bad parellisation strategey
+We created SWIFT for a number of reasons. The primary reason is that we want to
+be able to simulate a whole Universe! This has been attempted before (see
+[the EAGLE Project](http://icc.dur.ac.uk/Eagle) and [the Illustris project](
+http://www.illustris-project.org) for more details), but the codes used to do
+this have always been rather slow and difficult to modify. SWIFT aims to remedy
+those points by choosing to parallelise the problem in a different way and by
+having a more modular structure than other codes.
+
+The way that supercomputers are constructed is not by having one huge chip that
+everything runs on, but rather by having lots of different computers that are
+connected together by high-speed networks. Therefore the way to speed up your
+code might not necessarily be to make it 'run faster' on a single machine, but
+rather enable those machines to talk to each other in a more efficient way.
+This is how SWIFT is different from other codes that are used in Astrophysics
+for a similar purpose.
+
+Traditionally, you have each 'node' (computer) in the 'cluster' (supercomputer)
+running the exact same code at the exact same time, and at the end of each bit
+of the problem they all talk to each other and exchange information. SWIFT does
+this a little differently, with each node working on different tasks than
+others as and when those tasks need to be completed. This (theoretically)
+should cut down on the time when a node is sitting and waiting for work, which
+is just wasted time and electricity!
 
 ## What is SPH?