Shiny web apps
Learning how to use Shiny
Shiny is a tool for building web apps, using the R programming language.
RStudio's Shiny website is a good site to get the feel of. The Get Started page holds your hand, but you may want to jump into the Articles or Function Reference if you're looking for a speedy trial-and-error, results-first approach to learning to build your first few apps.
RStudio Education's Building Web Apps with Shiny is an interactive four-module course built with Shiny.
Shiny in Seven Lessons is a written tutorial by RStudio, on a series of seven pages. This is a good place to start.
https://mastering-shiny.org/ is a recent, comprehensive online book, by Hadley Wickham.
RStudio's readable-format documentation. This is what you should study.
Help pages for functions. Find syntax and options for functions here. Necessary when you use specific functions for the first time.
Weicheng Zhu's Shiny Tutorial is a simple Bookdown overview and reference for Shiny.
Geospatial Health Data: Modeling and Visualization with R-INLA and Shiny is a Bookdown online book, with an introduction to Shiny.
Outstanding User Interfaces with Shiny by Kenton Russel is an online book for those with a "solid knowledge of Shiny", to customise user interfaces.