TLS stands for The Times Literary Supplement — a British weekly paper about books and ideas. It comes from the same company as the London newspaper The Times, and it has been going since 1902. Each issue is mostly long reviews of new books, plus essays, poems, and letters where writers argue with each other about earlier reviews. It is written for people who read seriously — university teachers, writers, and people who simply love books — so the English inside it is difficult, much harder than a normal newspaper. When someone says "I read it in the TLS" or "she writes for the TLS", they are quietly telling you the book world takes them seriously. In writing you will see it as three plain capital letters, usually with 'the' in front: the TLS. You say the letters one by one: T-L-S. One thing worth knowing: outside the book world, these same three letters usually mean something completely different in computers (the security that puts the little lock in your browser), so the meaning depends entirely on what people are talking about.