Images can be made available under various different licensing arrangements.
These are some of the most common types:
Standard copyright (or "all rights reserved' copyright)
Images which are protected by copyright can been identified either by the word “copyright” or the copyright symbol “©” being used in the attribution. You need to obtain permission from the copyright holder to use / reproduce these images unless you can determine that you are able to rely on the exception in the Copyright Act for fair dealing for the specific purpose of research or study.
Most images which are available on Meta sites and/or Tripadvisor are protected by copyright. Permission will most likely need to be obtained from the copyright holder, this is generally the person who took the image, not necessarily the person who posted it, and not Meta or Tripadvisor. If a visible copyright statement accompanies the image indicating that it has been made available for use / reproduction under a Creative Commons (CC) licence, or if the image is identified as being in the Public Domain, then permission would not need to be sought. You would also not need to seek permission if you are able to determine that you can rely on the exception in the Copyright Act for fair dealing for the specific purpose of research or study.
Creative Commons (CC) licences are designed to allow the copyright holder to grant upfront permissions for the use / reproduction of an image under limited conditions. You are allowed to reprint and/or adapt an image that is made available under CC without getting permission from the copyright holder, though you are required to give credit to the original author in the form of a copyright attribution. CC licences do vary, so specific terms of individual images will need to be checked to determine what is permissible. CC licences are indicated by the words 'Creative Commons' or 'CC'. All forms of CC licences still require you to give credit to the original author in the form of a copyright attribution
Public Domain
Creative Commons Public Domain (CCO) allows the creator to put their image into the public domain and make it available for use and reproduction without being bound by copyright. You are allowed to reprint and/or adapt the image without needing to get permission from the copyright holder. Credit must still be given to the original author in the form of a copyright attribution.
If the copyright status of an image is not indicated i.e., there is no copyright statement then you need to treat the image as still being protected by copyright. Permission may be required to reprint and/or adapt the work. However, under the Australian Copyright Act, there are also provisions to use works in certain circumstances, including fair dealing for specific purposes.