Computer's really haven't changed.

It's like a bicycle. First we have push bikes, then peddle bikes, then geared bikes, motorised bikes, electric bikes and then hefty over 1,000cc bikes. They are still bikes.

It's the same with computers, instead of taking a whole building, to do a few actions we can now do the same thing with one tiny chip. We have compacted the computer and made a few more connections work faster but the principle is the same. Computers are still binary as they were when they started. Just a pile of on and off switches.

But now programmers have the luxury of using libraries which means they don't have to write 100 lines of code to make the letter 'a' appear on a certain part of your screen. Now they just have to include a library in their code.

Are you with me so far?

Then come packages that can be dropped into the programmers software, which is quicker and easier than writing all the 1,000's of lines of code which would be in that package. Remember this all gets translated back into machine code which is what the CPU is for (I am not going to talk about compilers and such like here, too confusing for most people).

Now we have apps to make our lives even easier. These are called higher level languages (anything that is not machine code is a higher level language).

Lastly we have plugins which are little bundles of software which do small functions for you. (Actually the latest thing is drag and drop, but I will leave that for the moment).

The reason they might slow up your website is because if they are not well written it might take your computer a long time to get these little suckers to work. If they are not friendly with other plugins then you have a problem.

When you pay for a theme which has 19 plugins, generally the people selling them have made sure the plugins are friendly with each other and work well together. They write the software that makes sure these plugins don't upset each other.

How Google algorithms work...