What is the primary difference between GraphQL and REST?

GraphQL lets clients request specific fields; REST returns fixed data shapes

GraphQL requires a specific database; REST works with any data storage

GraphQL uses XML for transport; REST relies exclusively on JSON objects

GraphQL is a server-side language; REST is a client-side routing library

In GraphQL, what is a query?

A read-only fetch operation used to request specific data from the server

A write operation used to modify existing records within the database

A persistent connection that pushes real-time updates to the client

A configuration file that defines the relationship between API types

What is the purpose of a GraphQL schema?

To define the types, fields, and operations available in the API

To manage the internal caching logic for expensive database calls

To encrypt sensitive field data before it is sent over the network

To automatically generate SQL queries based on client request shapes

What is a mutation in GraphQL?

An operation used to create, update, or delete data on the server

A validation function that checks if a query is syntactically correct

A way to combine multiple query results into a single JSON response

A specialized field that handles real-time data streaming via sockets

What is a resolver in GraphQL?

A function that populates the data for a specific field in the schema

A middleware component that handles user authentication and sessions

A tool that resolves naming conflicts between different schema versions

A client-side library used to normalize and store query results locally

In GraphQL, what is a scalar type?

A primitive leaf type representing values like String, Int, or Boolean

A complex type that groups multiple fields into a single object

A specialized query used to fetch large datasets in paginated chunks

A directive used to modify the behavior of a specific field or query

What does "strongly typed" mean in the context of GraphQL?

The server validates the query structure against the schema before execution

The API requires an encrypted connection to ensure data type integrity

The system only allows one specific database type to be used as a backend

The API is written in a language like TypeScript or Java for performance

What is a GraphQL fragment used for?

To define a reusable set of fields that can be shared across queries

To break a single large query into multiple smaller HTTP requests

To allow the server to return partial data if a database error occurs

To provide temporary authorization for specific sensitive fields

What is a subscription in GraphQL?

An operation that maintains a connection to push real-time data updates

A recurring billing model for users to access premium API endpoints

A way for developers to follow updates to the GraphQL documentation

A method for caching frequently accessed data on the client device

What does the term "N+1 query problem" mean in GraphQL?

Fetching a list of items results in one database call for every item

A security flaw where a single query can bypass N layers of protection

A schema design rule where every object must have at least N+1 fields

The maximum number of concurrent connections a single server can handle

In GraphQL, what is an "object type"?

A schema type that contains a collection of named fields and their types

The raw JSON response that the server returns to the client

A specialized input format used exclusively for mutation arguments

A reference to a specific row within a relational database table

What is a GraphQL argument?

A value passed to a field to customize or filter the data it returns

A logic error in the schema that prevents the server from starting

A specific type of resolver used to calculate mathematical results

A comment left in the schema to explain complex logic to developers

What does "introspection" mean in GraphQL?

The ability to query the schema itself to learn about its structure

A performance monitoring tool used to track resolver execution time

The process of optimizing database indexes for GraphQL queries

A security protocol that hides internal field names from the public

In GraphQL, what is a "non-null" type?

A field that is guaranteed to return a value instead of a null result

A data type that can only store numeric values like integers or floats

A validation rule that prevents users from submitting empty forms

A field that is hidden from the schema unless a valid token is provided

What is a GraphQL union type?

A type that allows a field to return one of several different object types

A method for merging two different GraphQL APIs into a single endpoint

A field that returns a list of items from multiple database tables

A specific type of resolver that connects to multiple data sources

What syntax represents a list of items in a GraphQL schema?

Wrapping the type name in square brackets, such as [User]

Placing a plus sign after the field name, such as User+

Wrapping the field name in curly braces, such as {User}

Adding the keyword "List" before the type name, such as List User

What is an "input type" in GraphQL?

A special type used to pass complex objects as arguments to fields

A field that accepts raw text input from a standard HTML form

A primitive data type like String or Int used for basic queries

A directive that forces a field to accept only uppercase strings

What is the difference between a root query and a root mutation?

Queries are for fetching data; mutations are for changing data

Queries are public; mutations require a private administrative key

Queries run on the database; mutations run on the local cache

Queries are limited to 10 fields; mutations have no field limit

What is a "directive" in GraphQL?

A modifier starting with @ that changes how a query is executed

A mandatory header required for every GraphQL request sent

A specific type of error returned when a resolver fails to run

A database command used to index fields for faster search results

What does the @deprecated directive do?

Marks a field as no longer supported to discourage its future use

Immediately deletes a field from the schema so it cannot be seen

Encrypts the field data to prevent it from being intercepted

Optimizes the field so it returns data much faster than others

What is the primary purpose of a "DataLoader"?

To batch and memoize data requests to reduce database overhead

To provide a visual progress bar for long-running API queries

To automatically upload files from the client to a cloud storage

To encrypt data during the transmission between server and client

What is a GraphQL "interface" type?

An abstract type that defines a set of fields multiple types must implement

A graphical user interface used by developers to test their queries

A connection between the GraphQL server and a third-party REST API

A configuration setting that enables multi-language support for the API

How are variables passed to a GraphQL query?

By defining them with a $ prefix and passing values in a JSON object

By hardcoding the values directly into the query string as text

By storing them in the server schema as static global constants

By appending them to the URL as standard query string parameters

What is "query complexity" in GraphQL?

A calculation of the resource cost of a query to prevent server abuse

A measurement of how many lines of code are in a specific resolver

A rating system used to identify how difficult a query is to write

The total number of unique types defined within the entire schema

What is "rate limiting" in GraphQL?

Restricting the number of requests a client can make in a timeframe

Slowly decreasing the speed of the API as the database grows larger

Limiting the number of fields a user can see based on their role

Setting a maximum file size for all image uploads via mutations

What is "schema stitching" in GraphQL?

The process of merging multiple underlying APIs into one gateway

The act of fixing broken types in a schema after a database update

A method for compressing the schema to reduce initial load times

The practice of manually writing schema files in a text editor

What is an "enum" type in GraphQL?

A special scalar that restricts a field to a fixed set of values

A dynamic list that automatically expands as more data is added

A numeric field that only accepts values between zero and ten

A type that combines multiple objects into a single search result

When would you use an "alias" in a GraphQL query?

To rename the result key of a field to avoid name collisions

To hide the real name of a database table from the end user

To create a temporary shortcut for a very long field name

To assign a nickname to a user within a social media application

Quizzes

GraphQL API Development Quizzes

GraphQL Fundamentals: Queries, Mutations & Schema Design

Mohammad Abu Mattar20 QuestionsBeginnerPublished: 26 Feb, 2026

Markdown for AI

GraphQL Fundamentals: Queries, Mutations & Schema Design

Up to 20 questions, shuffled on every run

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Welcome to the GraphQL Basics Quiz! Mastering GraphQL is essential for building efficient, flexible APIs that empower clients to request exactly what they need. This quiz will test your understanding of core GraphQL concepts like queries, mutations, schema design, and more. Each question is designed to challenge your knowledge and help you solidify your grasp of GraphQL fundamentals. Good luck!

Answer key and explanations20 questions

The quiz above draws 20 questions at random from these 28, so a second attempt will not be the same run. Everything in the pool is listed here.

What is the primary difference between GraphQL and REST?
AnswerGraphQL lets clients request specific fields; REST returns fixed data shapes
In GraphQL, what is a query?
AnswerA read-only fetch operation used to request specific data from the server
What is the purpose of a GraphQL schema?
AnswerTo define the types, fields, and operations available in the API
What is a mutation in GraphQL?
AnswerAn operation used to create, update, or delete data on the server
What is a resolver in GraphQL?
AnswerA function that populates the data for a specific field in the schema
In GraphQL, what is a scalar type?
AnswerA primitive leaf type representing values like String, Int, or Boolean
What does "strongly typed" mean in the context of GraphQL?
AnswerThe server validates the query structure against the schema before execution
What is a GraphQL fragment used for?
AnswerTo define a reusable set of fields that can be shared across queries
What is a subscription in GraphQL?
AnswerAn operation that maintains a connection to push real-time data updates
What does the term "N+1 query problem" mean in GraphQL?
AnswerFetching a list of items results in one database call for every item
In GraphQL, what is an "object type"?
AnswerA schema type that contains a collection of named fields and their types
What is a GraphQL argument?
AnswerA value passed to a field to customize or filter the data it returns
What does "introspection" mean in GraphQL?
AnswerThe ability to query the schema itself to learn about its structure
In GraphQL, what is a "non-null" type?
AnswerA field that is guaranteed to return a value instead of a null result
What is a GraphQL union type?
AnswerA type that allows a field to return one of several different object types
What syntax represents a list of items in a GraphQL schema?
AnswerWrapping the type name in square brackets, such as [User]
What is an "input type" in GraphQL?
AnswerA special type used to pass complex objects as arguments to fields
What is the difference between a root query and a root mutation?
AnswerQueries are for fetching data; mutations are for changing data
What is a "directive" in GraphQL?
AnswerA modifier starting with @ that changes how a query is executed
What does the @deprecated directive do?
AnswerMarks a field as no longer supported to discourage its future use
What is the primary purpose of a "DataLoader"?
AnswerTo batch and memoize data requests to reduce database overhead
What is a GraphQL "interface" type?
AnswerAn abstract type that defines a set of fields multiple types must implement
How are variables passed to a GraphQL query?
AnswerBy defining them with a $ prefix and passing values in a JSON object
What is "query complexity" in GraphQL?
AnswerA calculation of the resource cost of a query to prevent server abuse
What is "rate limiting" in GraphQL?
AnswerRestricting the number of requests a client can make in a timeframe
What is "schema stitching" in GraphQL?
AnswerThe process of merging multiple underlying APIs into one gateway
What is an "enum" type in GraphQL?
AnswerA special scalar that restricts a field to a fixed set of values
When would you use an "alias" in a GraphQL query?
AnswerTo rename the result key of a field to avoid name collisions