Biology is concerned with living organisms—with their structure, activities, distribution in space and time, and participation in evolutionary and developmental histories. Many of these organisms engage in activities that seem best understood in terms of information processing or representation. These include perception, cognition, signalling, and language use. We will not much be concerned with the role of concepts of information and representation in these cognitive contexts. For over the second half of the 20th century, biology came to apply informational concepts (and their relatives) far more broadly than this. For many biologists, the most basic processes characteristic of living organisms should now be understood in terms of the expression of information: the response to signals, the execution of programs, and the interpretation of codes. So although contemporary mainstream biology is an overtly materialist field, it has come to employ concepts that seem intentional or semantic. These come with a long history of causing foundational problems for materialists (and, to some extent, for everyone else).