OK for those of you that are unfamiliar with Object Oriented terminology (I couldnt be arsed typing Object-Oriented all the time so it will from now on be shorted to OO) here is a quick summary. An Object is a data structure that contains various bits of named data called properties and may contain various functions called methods that do things.
Objects are our friends, love them, hug them and call them George.
Why? Because they group related data and functions into a convenient package which naturally increases modularity and resuability of code. YIPPEE! Being a professionally lazy person I don't like working hard and constantly writing the same bit of code, to be frank, skunders my pish, anything that means I have to type less is an A+, Gold Star, goto the top of the class sort of thing to me! Not that has anything to do with OO programming of course thats just me being lazy.
In any OO language there may be many objects created from the same class. When often say that an object is an instance of the class and if we are being really geeky we don't create an object we instantiate it. So if you don't want to be laughed at but ubergeeks don't say "I have just made a HarveyWallBanger doobrydo from my Cocktail thingy" say "I have instantiated a HarveyWallBanger object from my Cocktail class" it will make you look way cool!