Once, my mother's brother asked me what software was, I said "for example, softwares were in my mobile phone", he said "open it, let me see it, can I touch it ?"
I think it's easier to explain programming than software. As for programming, you can give an example or a story to illustrate that, but how to explain software to a farmer with no knowledge about computer ?
In fact, my parents still have no idea about what I am doing in my office. How to explain software to them, as they have no knowledge about computer ?

Software is a bunch of prepackaged instructions that make a computer do something useful. Like a recipe.

The concept of software will obviously be harder to explain to someone unfamiliar with computers - I think the trick is relating it to something they do personally understand, and this is where the analogy to recipes and cooking can be useful: most people are familiar with the idea of carefully following the steps in a recipe in order to cook something.

Are they more familiar with other electronics such as a vcr that you might use as an example? If not, I'd look for a task where they are required to precisely follow steps, and compare software to a list of those steps.

I am working in the software department of a printer company (US-Japan Joint, in China), and we are developing embeded softwares for printers, and every time I went back to my hometown, my relatives would like to know what my job was, it's really a headache to explain that, because my hometown is in the rural mountain area, and older people have no idea about computer an printer.

Every time I said "Software is made by computer" or "Software is on the printer's motherboard","You can't touch, but they are there, you can only feel","they are only electrical signals", etc. the more explanation I made, the more confusion they get.

Couldn't you say something like 'you write the orders that the computer follows?'

Hands-on comparison:

Programming is going to school. Software is what they taught you in school (or uni). It makes you "function" properly in your everyday life and job.
You can look at the software in a cellphone as much as you can look at what's inside your brain.

Yes, don't focus on what you can't do with software (can't see it, can't touch it, only electrical signals, etc) and try to see what software does, and relate it to similar concepts in their everyday world. Like recepies, or orders. You tell the computer (in the printer in this case) how to do what it needs to do.

Maybe you need to start explain in simple terms how a computer is like a very eager but quite stupid worker, that needs to be told in detail what to do, but when told does it with extreme precision and speed.
And that almost all electronics today need a small computer to control how it works.

can't you just show then a Windows ME notebook and say: "Software is what you course, hardware is what you punch" ?

bad jokes apart,

if you can't tell what it is, show it.

The concept of software will obviously be harder to explain to someone unfamiliar with computers - I think the trick is relating it to something they do personally understand, and this is where the analogy to recipes and cooking can be useful: most people are familiar with the idea of carefully following the steps in a recipe in order to cook something.

The problem with the cooking analogy -- which has always bugged me -- is that there aren't complicated control structures in cooking. Most recipes don't contain loops or conditionals.

I think a better, but still pretty bad, analogy is putting together Ikea furniture from the cartoon instructions in that those things usually have something like a for-each loop: do this set of instructions for each of the table's four legs, etc.

An even better analogy, although more arcane, is folding origami from diagrams. In this case there's an actual formal language in play albeit a visual one. Origami diagrams have been standardized since the 60's or so. However, they don't ever contain anything like an if-statement. Is there any simple activity that does contain something like an if branch?

but how to explain software to a farmer with no knowledge about computer ?

I might try to explain it by using an example he might be more familiar with. How about...

A record player is hardware.
A record is a storage device.
The bumps and groves on a record is software.
The bumps and grooves are used to produce the desired output on the speaker which is sounds.

I'd draw the parallel for a computer except that I'm not as sure how to explain modern media storage techniques. Isn't it still more or less little bits of magnetic stuff that act similar to the bumps and groves on a record?

The above may be an appropriate description for someone that wants a more concrete definition of what software physically is but for all practical purposes, software is what you run on a computer to perform various tasks.