1 star means: This book is not worth your time or money, and I haven’t read more than the first 10 pages of the book. This book does not have a great plot, correct grammar, believable characters, nothing. (I don’t write detailed reviews about such books, because I haven’t read the book completely.) (the entire book is a problem)
2 stars means: This book has managed to capture my attention, initially. But lost it because it didn’t have a great plot or correct grammar or believable characters or anything else that I have mentioned in the review. (two problems and above)
3 stars means: The grammar, writing style is good, but the plot and characters are okay-ish. Either the plot is too generic, and the characters remarkable. Or the plot is unique and the characters are too stereotypical. (only one problem)
4 stars means: This book is a definite read, if you like the genre and the blurb of the book. Don’t worry about grammar, plot, characters, writing style: They all have passed my high standards.
5 stars means: This book is a paragon of excellence and I command you to buy it ASAP, irrespective of whether you read books from this genre or not. This book is a unique read, something that will make you stay up all night wondering why you exist.