It works essentially the same way as the phone apps do above. If you don’t care to let Google know what you do on a daily basis, you can make money from home by letting them monitor your Internet usage. They use the information they gather to help them market/increase the functionality of their advertising programs when targeting users that are similar to you.
With online jobs, there are many opportunities to specialize in your own area of expertise. You don’t need to do boring work to earn a living. As compared to the job market, one can settle on a job they do not love just to make ends meet. On the internet however, there are varieties of jobs to work on. Therefore, you can choose an area that best suits you and become an expert at it.
Do you enjoy fast food or going into retail shops? Many companies hire mystery shoppers to test the customer service of their stores. A common one is Subway, which hires mystery shoppers to ensure that "Sandwich Artists" are following all the franchise guidelines. If you have time and can travel to different places, this could be a good side hustle.