Image via Wikipedia
Pie chart attribution-ShareAlike 3.0
You need to know how to use photos copied and saved from photo sites, beyond the technology. Copyrights come into play, so you need to read the terms and conditions every time. Some photo sites include a variety of permissions. Always give attribution for your photo sources on blogs and web sites.
Know your rights; learn the meanings and conditions for use of combinations of CC, Creative Commons, photos, as in the pie chart at left.
Save allowed photos to a computer file.
Look for graphics that enhance your ideas, information, and presentation.
Flickr, Photoxpress, and other online photo sites have free photos. I have used Photoxpress for Baltimore Examiner articles. The article template helped meeasily insert photos and attribute them. (Baltimore Examiner is folding now. See article link, below.)
Your best photo source may be your digital camera.