Most advertisements follow certain conventions: they include a picture filling the background, a slogan, and a logo to help audiences identify the advertiser. Advertisements also aim to create continuity across multiple ads by keeping the same style of photography, font, and visual elements. Sometimes images are manipulated or seek to educate rather than promote a product directly. Ads may also contain just text or make use of intertextuality by borrowing elements from other media texts, sometimes for humor or irony.