Filler text is text that shares some characteristics of a real written text, but is random or otherwise generated. It may be used to display a sample of fonts, generate text for testing, or to spoof an e-mail spam filter.Filler text is text that shares some characteristics of a real written text, but is random or otherwise generated. It may be used to display a sample of fonts, generate text for testing, or to spoof an e-mail spam filter.