Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for automatic text suggestion are described. One of the methods includes receiving a text item including one or more terms; determining a plurality of text strings, each text string including a matching portion and one or more suffixes, wherein the matching portion matches the text item, and the one or more suffixes are located after the matching portion; ranking the one or more suffixes based on a credibility score and a frequency score of each suffix, the credibility score indicating an estimated credibility of a source of the text string including the suffix, the frequency score indicating an estimated frequency of appearance of the suffix; and providing a group of the one or more suffixes that includes a highest ranking suffix for display as a suggestion for completing a sentence starting from the text item.