As said:
Yuml is a free online tool for generating nice-looking diagrams that allow you to communicate your models dynamically without extra software.
Its a great way of easily and on-the-fly generating an image of you mean. We´ve all been using UML and similar constructs for years and this just makes it easier since we don’t need to regenerate stuff when we want to change something, we simply change the image request URI.
So how does it work?
You use an image tag and link to an image on the Yuml site. The query string (request URI) contains shorthand notation on how your model is supposed to look.
There´s a lot of example on the shorthand on this address: examples
Just to demonstrate, we could use this following URI to request a model describing a customer:
http://yuml.me/diagram/scruffy/class/%5BCustomer%5D-%3E%5BName%5D,%20%5BCustomer%5D%3C%3E1-0..*%3E%5BOrder%5D,%20%5BOrder%5D%3C%3E1-0..*%3E%5BOrderItem%5D,%20%5BCustomer%5D-%3E%5BPhoneNumber%5D,%20%5BCustomer%5D-%3E%5BCompanyName%5D,%20%5BCompanyName%5D-%5Bnote:This%20is%20a%20note%20on%20the%20notation%5D
Neat huh?