GMAT 2019 Syllabus
Knowing GMAT syllabus is the first step in preparation. Knowledge about GMAT syllabus gives shape to one's preparation.
Classification Of GMAT Syllabus
The syllabus comprises of four GMAT Exam sections

Analysis of Argument (Analytic Writing Assessment),

Quantitative Aptitude

Verbal Reasoning

Integrated Reasoning.
Analytical Writing Assessment
This is the first section of the GMAT 2019 Exam. This section includes ANY ONE of the following essays:
 Argument essay:
This essay will include a paragraph on a given subject, and the candidate will be responsible to find out the fallacies, inconsistencies, and contradictions in the essay. The estimated word count should be around 350 words.  Issue based essay:
In this essay, the candidate would have to write an essay for about 600 words on a given topic. The topic will be summed up in a couple of lines, and the candidate will have to write for or against the claim.
Articulation of the idea is a core component in writing essays. Keeping the paragraphs short and punctuating properly makes it easy for a reader to understand the text.
Using simple words with some idioms and phrases along with examples adds flavour to an essay.
Content is very important, giving appropriate titles helps one to impress the reader.
Quantitative Aptitude
The Quantitative Aptitude measures the ability to solve quantitative problems and interpret graphical data. It is comprised of two types of multiplechoice questions:

Problemsolving
 Data sufficiency
Both of the sections require a basic knowledge of Arithmetic as well as Elementary Algebra and common concepts in Geometry, mentioned below.
Arithmetic:

Number Systems & Number Theory

Multiples and factors

Ratio & Proportion

Real Numbers

Fractions

Decimals

Percentages

Averages

Powers and roots

Profit & Loss

Simple & Compound Interest

Speed, Time, & Distance

Pipes, Cisterns, & Work Time

Ratio and Proportion

Mixtures & Allegation

Descriptive statistics

Sets

Probability
Algebra:

Permutation & Combination

Monomials, polynomials

Algebraic expressions and equations

Functions

Exponents

Arithmetic & Geometric Progression

Quadratic Equations

Inequalities and Basic statistics

Equations

Solving Linear Equations with oneUnknown

Solving Linear Equations with Two Unknowns

Solving Equations by Factoring

Simplifying Algebraic Expressions

Solving Quadratic Equations
Geometry:

Lines and angles

Triangles

Quadrilaterals

Circles

Rectangular solids and Cylinders
 Coordinate geometry
Holding on to basics is the key. After getting fundamentals cleared a candidate can build on the concepts by practicing a lot on these above mentioned topics.
Verbal Reasoning
The Verbal Section measures the candidate’s ability to read and comprehend the given data and to reason and further evaluate arguments, followed by correcting the text or given sentence to form a standard written English.
Three types of multiplechoice questions are used in the Verbal section:

Reading comprehension  Candidate will be given a passage, which they have to understand and answer the related questions. To understand the given passage in a better way, one has to practice reading on a daily basis.

Sentence correction  A grammatically incorrect sentence will be provided, with 5 alternatives, one of which will be correct.

Critical reasoning  A short passage will be given, and then answer questions based on its premise and conclusion. A candidate has to think critically i.e approach the question from the point of view of a critic.
Integrated Reasoning
This section measures your overall ability to understand and evaluate multiple origins and types of information like verbal, numeric and graphical.
This is the second section of the GMAT. Following are the type of questions asked in the integrated reasoning section.
MultiSource Reasoning:

These questions are in the form of multiple tabs, which the candidate can navigate across.

The questions involved are generally from critical reasoning and sometimes quantitative reasoning might also be involved.

An online calculator is provided to help with calculations.
Table Analysis:

A table is given to the test taker along with 3 questions and each question will have 2 choices.

The test taker must be able to accumulate useful data and exclude the unimportant data in order to solve the question in a short period of time.
Graphics Interpretation:

A form of the graphic presentation will be displayed  either a chart or a graph.

The candidate will have to analyze the information present in the graph and be able to answer two questions each for every graph.

A minimum of three choices will be given to choose from.
TwoPart Analysis:

A question prompt is given and has a small table related to it.

The test taker has to choose 2 answers out of 6 options that are available.
Other Important topics

Pronoun Agreement

Pronoun Ambiguity

The Test Masters Catalog of Idioms

Misplaced Modifiers

Parallel Construction

Verb

Tenses

Subject/Verb Agreement

Noun Agreement

Comparison Words

Quantity Words

Redundancy

The Subjunctive Mood

Indirect and Direct Speech

Active and Passive Voice

Sentence Structure

Punctuation
A prospective candidate aspiring to score over 800 as GMAT exam score must not omit any single topic but focus on each and every topic in depth.