Essentially, close reading means reading to uncover layers of meaning that lead to deep comprehension. The Partnership for Assessment of Readiness for College and Careers (PARCC) supplies clarification useful for teaching with Common Core standards in mind:
Close, analytic reading stresses engaging with a text of sufficient complexity directly and examining meaning thoroughly and methodically, encouraging students to read and reread deliberately. Directing student attention on the text itself empowers students to understand the central ideas and key supporting details. It also enables students to reflect on the meanings of individual words and sentences; the order in which sentences unfold; and the development of ideas over the course of the text, which ultimately leads students to arrive at an understanding of the text as a whole. (PARCC, 2011, p. 7)
For the rest of the article, including three tips for working with close reading, click here.