An asset is any possession that holds or grows in monetary value. Most people work to put money in the bank and pay bills, but the wealthy acquire assets that grow. The super wealthy 1% in America tend to be corporate executives. They are compensated with salaries, but most of their millions and billions come from company stocks. If we want to fix the income gap, regular people either need to have company equity of their own, or be made aware of the many types of assets outside of their jobs.
This YouTube video by The Better Men Project lists 10 types of assets in use today. Some of them have barriers to entry, but others can be created with personal computers and smartphones.