Simple Decentralized App Architecture

Two Key Technologies:
IPFS: A distributed datastore modeled after BitTorrent and Git. Soon it will have an incentivisation layer in which you pay strangers to store your content. Basically, a P2P AWS.
Ethereum: A single shared computer living on the network, modeled after Bitcoin. It's essentially a computer everyone can trust to store data and to execute code.
Basic Dapp Architecture

To give context for the diagram, consider the application flow of a crowdfunding Dapp modeled after Kickstarter:

Client Side

Perform a DNS lookup to receive a hash of your dapp
Download the dapp from peers on IPFS
Load your HTML/JS/CSS
Lookup the most recent crowdfunding projects on Ethereum
a. Each project will contain a hash of the pitch video, content, and rewards
Use the hash to download a project's content from IPFS
Send ETH (Ethereum's currency) to fund the project
Ethereum Side

The croudfunding smart contract receives the ETH payment.
Once the deadline for the project crowdsale ends, the contract either pays the project creator or returns the funds to the funders.
In this example, our global state contains the list of current projects, references to their content, and simple logic for the payout. IPFS contains the Dapp code and project content.

With these simple building blocks, it is possible to create powerful applications.
(copied from publication "karl.tech/simple-dapp-architecture")