Updates and other decisions are made by the ‘miners’. Miners use computers or specialized hardware to generate large amounts of computer processing power, and this is used to operate the network and process transactions. In return, they receive transaction fees. They will also receive freshly generated bitcoins until the last bitcoin of the 21 million BTC supply is ‘mined.’ At the current pace of mining, this will happen in the year 2140. If Bitcoin is still around, the miners will be incentivized to do their work for the fees alone, keeping the network up and running.
In the case of Bitcoin, miners run computer programs to verify the data that creates a complete transaction history of all Bitcoin. A technology known as the blockchain, which is used to create irreversible and traceable transactions, makes the process of verification possible. Once a miner has verified the data (which comes in a block, hence, blockchain), they are rewarded with some amount of digital currency, the same currency for which they were verifying the transaction history. So mining Bitcoin, for example, would earn you Bitcoin.
Ripple positions itself as a complement to, rather than a competitor with, Bitcoin - the site has a page dedicated to Ripple for bitcoiners. Ripple is a distributed network which means transactions occur immediately across the network - and as it is peer to peer - the network is resilient to systemic risk. Ripples aren't mined - unlike bitcoin and its peers - but each transaction destroys a small amount of XRP which adds a deflationary measure into the system.