I meet many friends who don't know how to earn online. So, I thought to make a list.
Sometimes making a living or earning online while traveling is just about knowing where to look for information. It's not easy, but it can be adventurous.
Sometimes just having a laptop and some dedicated time, it's possible to earn money. Initially it's difficult, because you need to build a portfolio so that you can convince people that you will be able to provide quality service. It can be frustrating, but also rewarding.
These jobs are typically not stable careers, but if you are resilient enough, you can make decent living. Also, some people travel to Asia or places which are not expensive where you can easily get by earning few dollars a day.
Some example jobs:
a) Teaching english or other language over skype or other web conferencing program
https://www.dailywritingtips.com/make-money-teaching-engli…/
b) Translation
https://speakt.com/translators/
https://unbabel.com/translators/
c) Data labeling on Amazon mechanical turk https://www.mturk.com/
g) Graphics design, designing T-shirts (http://redbubble.com), stickers etc.
h) Dog walking, baby sitting what not..check http://craiglist.com basically doing something for someone else when the job provider don't have time but you have time. etc.
i) Uber also falls into this category.
http://uber.com
j) For housewives who have babies and can't afford to go outside
k) Being a photographer, model, youtuber, blogger, vlogger and earning through ad reveneue.
i) Delivering packages (http://roadie.com)
j) Eearn with crypto websites. Basically earn tokens that can be exchangeable with dollars.
Blog on http://hive.com/blog and earn steem
Vlog on d.tube and earn DTC http://d.tube
Change from Chrome/Mozilla to Brave browser and earn BAT token.
There are also job platforms where you can search by category. Typically you create your portfolio here, get recommendations from people you worked with.
- http://upwork.com
- http://guru.com
- http://toptal.com
Some others: https://www.hostinger.com/tutorials/best-freelance-websites
Some others videos: 
Even craiglist.
Find some more in this quora: https://www.hostinger.com/tutorials/best-freelance-websites
Read make money traveling for more options:
https://www.claimcompass.eu/blog/make-money-traveling/
Everything is on the internet. You just need to be patient and dedicated, and figure out what you like to do.
Good luck.
Read the backpacker's tale
http://abackpackerstale.com