Introduction
A web application is a program stored on a remote server and delivered over the Internet through a browser interface. Creating a web application has become a significantly easier task nowadays because of the different Web frameworks present in the industry. Sinatra is one of the web frameworks written in Ruby language that can be used to create Web Applications and services.

Let’s learn about the Sinatra web framework.
About Sinatra Framework
Sinatra is an open-source framework developed in Ruby. It is a Domain Specific Language (DSL) for quickly creating web applications in Ruby with minimal effort. It is intended to be a simple yet extremely powerful and versatile way to develop web-delivered applications with minimal setup, configuration, or effort. Basically, Sinatra makes it quick and simple to launch a web service.

Sinatra leverages the fundamental capability of the Ruby programming language by allowing you to map incoming web requests to blocks of Ruby code. It builds on a Rack to do this. Rack is a webserver interface that allows Ruby frameworks to deal with HTTP or Web communications systematically. It enables you to manage any HTTP request and the pipeline of actions you may need to address, such as authentication, caching, and more, to provide a fantastic web-based software experience.
A basic app in Sinatra will look like this:-
# app.rb
require 'sinatra'
get '/' do
'Hello Ninjas!'
end