There is an inverse relationship between print size and resolution (if you increase the print size the resolution decreases and vice-versa).
To get good results when inserting an image into a research poster, the image should be printed at a resolution of at least 200 pixels per inch (ppi).
Images that look good online may not be high enough resolution to look good in print at the size you want them to be.
Watch the video below to see these concepts in action:
Attribution means:
You let others copy, distribute, display, and perform your copyrighted work - and derivative works based upon it - but only if they give you credit.
Noncommercial means:
You let others copy, distribute, display, and perform your work - and derivative works based upon it - but for noncommercial purposes only.
No Derivative Works means:
You let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it.
Share Alike means:
You allow others to distribute derivative works only under a license identical to the license that governs your work.