How to Correctly Credit Content
Using someone's content - without crediting the originator - is frowned upon online. However, if respectfully reposting the creative works of others is a grey area for you, here's a quick guide on how to credit content. Always remember, if you didn't create it then you should credit it.
When reposting images and graphics, make the source somewhere visible (aka don't hide the username below or amongst hashtags). In the case of phrases and captions, never copy and paste someone's words and claim them as yours. Restate the writer in quotation marks and prefix an acknowledgment to the quote.
Be courteous; you could contact the creator to request permission before posting their work. It is not enough to say that the image belongs to Pinterest as Pinterest is merely a search engine. Save the image as the creator's name so that you can credit the owner. Or you can try using an 'image reverse search' tool to trace the source and find the first location of the photo or infographic. If you can't find the owner, don't repost. Free image searches are always a viable option.
The point is to give credit. Stating "source unknown" is better than saying nothing at all. Saying nothing gives the impression you own rights when you don't. So be sure to credit content in your writings and posts.