Photography is an art, a communication media, a way to remember past memories but also something one can do for ones living. Here below a few useful links:
Showcase your work
Selling your pictures
Corbis
Getty
Shutterstock
EyeEm
Adobe Stock
Professional services
Blurb: high quality books
Find and fight images theft
Pixsy: limited coverage in terms of countries but unique offering and well executed as a streamlined one-stop-shop to recover fees from unauthorized images