No, not without permission. One of the rights that copyright conveys is right to display the work publicly. By placing the copyrighted work in your portfolio, everytime you show it you are usurping the original artists right.
an artist should have a portfolio
In all likelihood no.Ostensibly your portfolio is designed to generate revenue for you. This would be a commercial use of the copyrighted material and would probably disqualify it as "fair use"
The copyright holder, or anyone the copyright holder authorizes.
No. Public domain means that the material is available for use by anyone, without copyright restriction.
You may use copyright protected material when you are the copyright holder, or when you have permission from the rightsholder or an exemption in the law. The most notable exemption is fair use or fair dealing, which allows certain limited unlicensed uses in situations such as education and commentary.
Contact the copyright holder and request permission.
A) Use only original material B) Use only material confirmed to be in the public domain C) Find the copyright holder of any other material and, in writing, obtain the necessary permissions.
Infringement is the use, without permission, of copyrighted material that does not fall under a "fair use" or other exception to copyright law,
You would be guilty of copyright infringement, a federal crime.
Unless it would fall under "fair use" no it is not "okay" to use copyrighted material without permission
To determine if material posted online is copyrighted, look for a copyright symbol (), the word "copyright," or the phrase "all rights reserved." Additionally, check for any statements or disclaimers indicating the material is protected by copyright law. You can also search for the material in copyright databases or contact the creator for permission to use it.
Copyrights protect the "owner" of that material. To use or reproduce it without express approval of the "copyright" holder is illegal. "Copyright Laws'" protect intellectual property from unauthorized use.