“There are two terms that get thrown around, stack language and concatenative language. Both define similar but not equal classes of languages. For the most part though, they are identical.

Stacks are a pretty fundamental concept in computer science, and many languages use stacks internally in the implementation. Any language that allows recursive definitions uses some type of call stack to save return addresses between function calls, and often the same stack is used to spill values which cannot be allocated in registers. However, this is just implementation detail, and this call stack is not exposed directly to the programmer (except in languages with first-class continuations; I'll touch upon this later).

So what makes stack languages different? The key concept here is that there are multiple stacks: all stack languages have a call stack to support recursion, but they also have a data stack (sometimes called an operand stack) to pass values between functions. The latter is what stack language programmers mean when they talk about "the" stack.

Most languages in widespread use today are applicative languages: the central construct in the language is some form of function call, where a function is applied to a set of parameters, where each parameter is itself the result of a function call, the name of a variable, or a constant. In stack languages, a function call is made by simply writing the name of the function; the parameters are implicit, and they have to already be on the stack when the call is made. The result of the function call (if any) is then left on the stack after the function returns, for the next function to consume, and so on. Because functions are invoked simply by mentioning their name without any additional syntax, Forth and Factor refer to functions as "words", because in the syntax they really are just words.”

“At a conference about ideas, it’s important to step back and consider the engine that creates them: the human mind. How exactly does the brain — a three-pound snarl of electrochemically frantic nervous tissue — create inspired inventions, the feeling of hunger, the experience of beauty, or the sense of self — and how reliable is it?”

“It would change the musical world as we know it.”

“While all monasteries are beautiful and mysterious in their own way, there are some that stand out from the rest.”

“Consider a photo of someone you think is you eight years ago.”

“Cinema 4D is a high-end 3D graphics application capable of procedural and polygonal modeling, animating, lighting, texturing, and rendering.”