Talking about Motion: A crosslinguistic investigation of lexicalization patterns Book

This book aims to give a comprehensive account of grammaticalization. It serves as a great introduction to this linguistic notion. it also serves as a good textbook for whoever interested in linguistics. The term "grammaticalization" is thought to have originated with Meillet (1958, but first published in 1912). It has been utilized in different linguistics fields, such as: syntax, morphology, semantics and pragmatics.
Hopper and Traugott define grammaticalization as a process of linguistic change whereby an autonomous lexical unit gradually acquires the function of a dependent grammatical category. The grammaticalized word, then, continues to develop new grammatical functions. It is worth mentioning that forms do not shift abruptly from the lexical category to the grammatical one, but they go through a series of small transitions, transitions that tend to be similar in type across languages. This process is also accompanied by a gradual disappearance of segmental and suprasegmental phonological features. In addition, grammaticalization involves a loss of semantic content. It can also be analyzed from two different dimensions: synchronic & diachronic.
There are many other linguistic phenomena that have been tackled by the book. It's a must-read if you are considering becoming a linguistics major !