What is the difference between a model and a library class, and helper class?
How do I know when a class is a helper class and not a library?
I'm intersted in this information so I can properly organize and place my class files into the correct folders in my php MVC structure.
Based on summary of the Helper versus Library definition here difference between libraries and helpers in php frameworks, but adding in the Model aspect:
Helper - often a set of related functions, rather than classes, that help with,make it easier to, work with some existing functionality/component, eg. arrays, strings, urls, etc. for example - http://laravel.com/docs/helpers
Library - A larger collection of utility classes/methods that provide some sort of coherent functionality, eg. image manipulation, external api access, etc.
Model - in general a model would represent some aspect of the domain that you are 'modelling' in your application. A model could represent a single entity within your domain, eg. if you are writing a project management tool you might have separate models for Organisation, Project, TeamMember, etc.