Synthesized answer
The book "How to do things with words" by J. L. Austin presents his research over the last decade of his life [Passage 1]. A central development in this work is Austin's abandonment of his earlier distinction between performative utterances and statements [Passage 1].
Instead, Austin introduces a more comprehensive theory of "illocutionary forces" of utterances [Passage 1]. This new theory has significant implications for numerous philosophical issues [Passage 1]. The provided passage describes the book's focus on these key concepts but does not elaborate on the specifics of how to explain them in one's own words.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: How to do things with words by J. L. Austin Description: This work sets out Austin's conclusions in the field to which he directed his main efforts for at least the last ten years of his life. Starting from an exhaustive examination of his already well-known distinction between performative utterances and statements, Austin here finally abandons that distinction, replacing it with a more general theory of 'illocutionary forces' of utterances which has important bearings on a wide variety of philosophical problems.