There are rules and regulations for using images. You can’t just grab an image from google search and use it without permission.
Have a look at the web pages I have posted on in this section page that will lead you to most popular royalty-free image sites.
A Collection of Web Pages Related To Copyright Free Images
Sites Offering Public Domain Images
Public domain images are free to use for anyone. The public domain allows the use of the content for any purpose free. The purpose of the public is not for profit but as a public service. People contribute to the public domain and others use the content.
Have a look at the resources to follow listing public domain images.
Web Pages I have Selected Related To Public Domain Images
Understanding Image Copyright Laws
With these laws in place it encourages people to create. If there were no laws, people may be worried about people using their work and would be discouraged with creating new work.
Web Pages I have Selected Related To Image Copyright Laws
All you need to know about Copyright licenses
When using other’s people work you can purchase a license to use the work legally.
For example, a photo may have a license for using it in editorial content, while there is another license for marketing.
There also may be restrictions of how many images you can distribute. Have a look at the resources I have collected related to Copyright licenses
Web Pages I have Selected Related To Copyright Licenses