I signed an NDA, what is this?
An NDA (non-disclosure agreement) is an agreement confirming that you will not disclose any information about the shoot that you are on and the legal consequences of breaking the agreement. These are often comprehensive and include social network sites, so please be mindful of the terms of the agreement and take seriously the commitment you are making. This is normal and a necessary part of being involved in the media world and your agent will usually have reviewed the document prior to the shoot. However, if you have any questions about the content of the NDA, feel free to contact your agent and check with them before signing. You should not accept any job as a supporting artist if you are not willing to keep the confidentiality of the project.
In summary, do not mention any projects you are working, or may be working on, on Facebook, Twitter or any other social networking site, anywhere online and background artists should not as a general rule list themselves as cast members on IMDB.