In a word...yes! But of course, there are exceptions--remember that in the case of the CC0 license, the creator has relinquished all conditions for reuse of their work, including attribution. Unsplash is a great example of an image database that doesn't require attribution, but does recommend the use of its own automatically generated attribution notices in order to help their photographers get more exposure and continue to share it.
Since 2004, however, Creative Commons has made attribution a standard part of their licenses after 98% of their users selected attribution licenses, and, of course, considering that creators can deny this condition of their license.
In any case, it's a good idea to get in the habit of attributing the material that you reuse, regardless of whether the license requires it or not. Why? Because it supports Creative Commons's central mission of "Encouraging the ecology of creativity" wherein users of the world's information are not merely receptacles of it, but are able to actively contribute and share it.
While there is no consistent attribution style guidelines to the extent that style guides like MLA or Chicago style set for citations, there are some common elements that should go into an attribution. According to the Creative Commons Wiki, they are:
Title, Author, Source, License
A good rule of thumb is to use the acronym TASL, which stands for Title, Author, Source, License.
Title - What is the name of the material?
- If a title was provided for the material, include it. Sometimes a title is not provided; in that case, don't worry about it.
Author - Who owns the material?
- Name the author or authors of the material in question. Sometimes, the licensor may want you to give credit to some other entity, like a company or pseudonym. In rare cases, the licensor may not want to be attributed at all. In all of these cases, just do what they request.
Source - Where can I find it?
- Since you somehow accessed the material, you know where to find it. Provide the source of the material so others can, too. Since we live in the age of the Internet, this is usually a URL or hyperlink where the material resides.
License - How can I use it?
- You are obviously using the material for free thanks to the CC license, so make note of it. Don't just say the material is Creative Commons, because that says nothing about how the material can actually be used. Remember that there are six different CC licenses; which one is the material under? Name and provide a link to it, eg. http://creativecommons.org/licenses/by/4.0/ for CC BY.
- → If the licensor included a license notice with more information, include that as well.
Lastly, is there anything else I should know before I use it?
- When you accessed the material originally did it come with any copyright notices; a notice that refers to the disclaimer of warranties; or a notice of previous modifications? (That was a mouthful!) Because that kind of legal mumbo jumbo is actually pretty important to potential users of the material. So best practice is to just retain all of that stuff by copying and pasting such notices into your attribution. Don't make it anymore complicated than it is -- just pass on any info you think is important.
These best practices are based on actual CC license requirements. Noting the title is a requirement of all CC licenses version 3.0 or earlier, optional for 4.0. Noting the author, source, license, and retaining any extra notices is a requirement of all CC licenses. See Devil in the details.
Devil in the details
If you have any doubts or questions, you can read the complete attribution requirements which are spelled out in detail in the legal code of every CC license, eg. http://creativecommons.org/licenses/by/4.0/legalcode#s3a. This chart compares the detailed requirements across all versions of CC licenses.
Don't make it too complicated
The license tells you to be reasonable:
- You may satisfy the conditions in (1) and (2) above in any reasonable manner based on the medium, means and context in which the Licensed Material is used. For example, it may be reasonable to satisfy some or all of the conditions by retaining a copyright notice, or by providing a URI or hyperlink associated with the Licensed Material, if the copyright notice or webpage includes some or all of the required information.
There is no one right way; just make sure your attribution is reasonable and suited to the medium you're working with. That being said, you still have to include attribution requirements somehow, even if it's just a link to an About page that has that info.
If all else fails, you can try this Attribution Generator--but make sure that you compare that attribution with the CC guidelines.
First and foremost, if you see an attribution or CC license on an image you'd like to use and it has been prepared correctly, there should be a link or links that guide you back to the original creator and/or material. That's a perfect opportunity to check that you can indeed use the image in the way you think you can--the closer you get to the original source or creator, the more authoritative the information about the license is. If the attribution is incomplete or the metadata associated with the image seems vague, you may want to approach it with some caution and conduct some additional research.
Once you've checked that the license and attribution are correct, check to see if there's an attribution generator on the platform you've found the image on--for example, Wikimedia gives you the option to generate an attribution along with the metadata that should show you the original source of the image.