Some things are not protected by copyright. For example, copyright does not protect factual information or data, titles, short word combinations, names, characters, slogans, themes, plots, or ideas. These may be used or copied without permission or payment of royalties (unless they happen to be protected under trademark law).
Similarly, materials in the public domain can be copied freely, either because copyright protection has lapsed or because the copyright owner has indicated general permission to make copies. If the latter is the case, make certain you comply with any constraints the owner may have indicated regarding reproduction of the material.