4. A computer-implemented method for aligning content, the computer-implemented method comprising: as implemented by one or more computing devices configured with specific computer-executable instructions, obtaining a textual transcription of an item of content comprising audio content; identifying a portion of the textual transcription that includes text also included in a portion of a companion item of textual content, wherein the textual content includes body text and matter other than body text; determining a level of correlation between words in the portion of the companion item of textual content and words in the portion of the textual transcription; determining that the level of correlation satisfies a threshold value; in response to determining that the level of correlation satisfies a threshold value, identifying the portion of the companion item of textual content as including body text; identifying a second portion of the companion item of textual content that does not satisfy the threshold value with respect to any portion of the textual transcription; determining that the second portion of the companion item of textual content that does not satisfy the threshold value is front matter based at least in part on a determination that the second portion of the companion item of textual content that does not satisfy the threshold value appears within the companion item of textual content prior to an earliest portion of the companion item of textual content for which a corresponding portion of the audio content is identified; and generating content synchronization information that indicates (a) portions of the audio content that correspond to body text of the companion item of textual content and (b) further indicates that the matter other than body text in the textual content does not correspond to any portion of the audio content, wherein the matter other than body text includes the second portion of the companion item of textual content determined to be front matter, wherein the content synchronization information indicates that the body text included in the portion of the companion item of textual content should be presented in synchronization with a portion of the audio content that corresponds to the body text included in the portion of the textual transcription.
4. A computer-implemented method for aligning content, the computer-implemented method comprising: as implemented by one or more computing devices configured with specific computer-executable instructions, obtaining a textual transcription of an item of content comprising audio content; identifying a portion of the textual transcription that includes text also included in a portion of a companion item of textual content, wherein the textual content includes body text and matter other than body text; determining a level of correlation between words in the portion of the companion item of textual content and words in the portion of the textual transcription; determining that the level of correlation satisfies a threshold value; in response to determining that the level of correlation satisfies a threshold value, identifying the portion of the companion item of textual content as including body text; identifying a second portion of the companion item of textual content that does not satisfy the threshold value with respect to any portion of the textual transcription; determining that the second portion of the companion item of textual content that does not satisfy the threshold value is front matter based at least in part on a determination that the second portion of the companion item of textual content that does not satisfy the threshold value appears within the companion item of textual content prior to an earliest portion of the companion item of textual content for which a corresponding portion of the audio content is identified; and generating content synchronization information that indicates (a) portions of the audio content that correspond to body text of the companion item of textual content and (b) further indicates that the matter other than body text in the textual content does not correspond to any portion of the audio content, wherein the matter other than body text includes the second portion of the companion item of textual content determined to be front matter, wherein the content synchronization information indicates that the body text included in the portion of the companion item of textual content should be presented in synchronization with a portion of the audio content that corresponds to the body text included in the portion of the textual transcription. 9. The computer-implemented method of claim 4 , wherein the item of content comprising audio content is an audiobook.