Micro jobs are small tasks assigned to the registered members, to be finished within a timeframe. Each of these jobs are paid after a review by the provider or employer. Quality is important. Depending on the country of the user, various tasks will be available. Some of the popular crowd sourcing sites are given below:
There are numerous other sites which offer micro jobs. Among the above, Microworkers and Rapidworkers offer more jobs.
To get an idea on the nature of jobs, please refer the screenshots below:
You will be asked to test apps, post comments on YouTube, Sign ups, do searches, take surveys and many others. The amount is usually less as the tasks are small. It is important to select only the work you can finish as quality is important. It will be good if you use a separate email id for this as you will be signing up at many sites which will start sending mails and soon your inbox will be full. Many of such sites have set a threshold of $10 after which only you will be able to withdraw money. You would need a PayPal account.
Some of the tasks include writing reviews in Amazon. Other tasks ask you to create a YouTube channel and hand over the credentials as proof. But I doubt how safe it is to hand over the details.
I generally prefer doing surveys more, as our privacy is taken care of. Just try this and if you find interesting then proceed.