java - Why IDs start with com.? -

like one:

<widget xmlns     = "http://www.w3.org/ns/widgets"         xmlns:gap = "http://phonegap.com/ns/1.0"         id        = "com.phonegap.helloworld"         version   = "1.0.0"> 

i see in java , android.

what com mean? phonegap here? company or web site of company?

there's no technical reason why ids or package names must start com. however, no 2 apps can have same package name, convention name app based on website's url in reverse. convention means no 2 apps conflict, @ least long ownership of domaian doesn't change. in case, made phonegap.com, package name com.phonegap.xxx, x name pick.

phonegap cross-platform app development tool, can write 1 set of code both android , ios.