○ Parcel is a 'bundler' which grabs ./src/index.html and interprets the required files and their associated dependencies - it is efficient because it only includes the bits of the dependencies actually used rather than everything, making the code transferred to the user smaller. It also allows us to use the import method for including dependencies in the browser code, which is more powerful (but note is not yet supported by Node on the server - you still need to use require on the server). Parcel does not really support PWA apps at this time, and tries to rename files that shouldn't be (e.g. sw.js and default.html) which confuses the code which uses them!