when npm install command runs, It installs all the packages mentioned in the package.json.
when pod install command is run, which is the base file to install all required pods?
Is there any file in iOS like package.json that decides which pods have to be installed?
The Podfile itself. It's a ruby file looking something like this:
# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'
target 'ProjectName' do
# Comment the next line if you don't want to use dynamic frameworks
use_frameworks!
pod 'Alamofire', '5.6.2'
end