Computer assemblers are the core of what helps to make our modern world of computers and software revolve. Without them, our world would be a significantly different place.
Every program on the computer is composed of sets of electrical instructions that are given to the computer's CPU, telling it what to do. These are referred to as 'operation codes', or 'op codes' for short. In the olden days of computers, these instructions were given through slow and inefficient methods, such as inputting each of these commands bit by bit.
With the development of the Assembly programming language, this all changed. Finally, computer programmers had a way to program the computer using a fairly human readable method. This allowed for them to make much longer programs, as well as more complex programs.
Computer assemblers take a file filled with source code, written in the Assembly programming language, then translate that into something that the computer can understand. At their core, this is all that computer assemblers do; they are the translators that computer programmers can use to 'speak' to the computer.
However, as they have evolved, computer assemblers themselves have grown more and more complex. Rather than just translating every single instruction in the source code file into the corresponding computer operation code, they can turn more complex statements that the computer would not understand into a series of corresponding operations that the computer will understand.
Computer assemblers are at the heart of all computer programming. While computer programmers have moved on to use other programming languages, such as C or C++, computer assemblers are still at the heart of everything computer programmers do. Without these clever little programs, computer programmers are able to make computer programs quickly and efficiently, with levels of complexity in them that earlier generations of programmers never would have dreamed of.