Hello @karenb54 , put in a simple way: witnesses are those who provide the technical support for this platform to work, they are voted in so that it is completly descentralized, witnesses vote on certain issues that are important for all users: APR paid to SBD holders, price feed STM/SBD, account creation fee.. etc

I am currently witness number #41, if you wish you can vote for me :)

For further questions you can also reach me on steemit.chat