Essential Korean Grammar is designed for people who already know a bit of Korean and wish to speak and write the language correctly and naturally—as Koreans do!
This book is a great resource for reviewing for an exam, preparing for a business meeting, or traveling to Korea for work or pleasure. Accessible to learners at any level, it synthesizes all the essential Korean grammar points and presents them in a compact and logical form, and enables you to build up a natural-sounding fluency.
Essential Korean Grammar is a toolbox to help you form correct and natural-sounding sentences, and determine which grammar you need for reading or writing Korean. It details:

Expressing yourself clearly the way native Korean speakers do

How to use Korean expressions, idioms and sentences correctly

Avoiding common grammatical errors made by non-native speakers

Communicating using simple, everyday vocabulary and sentences

The grammar items are cleverly rated so you can determine what's most useful for you to study, based on your Korean knowledge level and your plans. The star rating system ranges from 5 stars ("critical"; with these under your belt you can communicate almost everything you need to say) to 1 star (don't worry about this unless there's some reason you need to know it—for example, the TOPIK exam).