If the commercial suppliers want to sell hybrid seed, the way you described it is what happens. They have to keep cross pollinating the parents to produce the hybrid, year in, year out. There are of course techniques to make it easier (which often means a small percentage of undesirable seed - but small enough to be tolerable) and there are countries where labour is cheap and skilled.
Of course occasionally, and this isn't very common (at least I hope it isn't), what a company calls a hybrid is in fact not a hybrid but a normal open-pollinated variety.
You can always save seed from a hybrid (provided it produces seed and that seed is viable) and grow it out just to see what happens. Amateur tomato breeders do this all the time - make a cross and plant out each successive generation. Of course if nothing shows up that is of any interest you move on to the next cross.
Hope I've explained it clearly enough.

Hybrids can be produced from two pure breeding lines for a given trait ... for example AA X aa .. this will always produce a hybrid of Aa where one gene "A" from one parent wiil combine with a gene "a" from the second parent ... the result is always 100 % of the progeny will be Aa or hybrids. Crossing hybrids is where the problem surfaces since Aa X Aa that is a cross between two hybrids will produce 25 % AA the original pure line and 25 % aa the other pure line and only 50 % will still be hybrids Aa ....

I hope that makes some sense ... I'm not a propagator just some basic theory ... perhaps someone cann add to it ...

Good Day ...

So therefore, it is easy to reproduce the same hybrid as long as the parents are not hybrids themselves? And this process can be repeated again and again, easily, so that the same hybrid plant will be produced and the sale of these seeds are guaranteed? And this is how it is done?

Wow!

Obviously now my question is how do they go about hybridizing. No one needs to answer this for me, I see that this question has been asked and there is a wealth of information about it. It is all a mystery to me, very fascinating!

I was just curious of whether or not it is a difficult process to mass produce these seeds.

Now, the next question is: when a plant, any kind of plant, is "improved" hasnt some form of hybridizing occured in order to make the improvement? It seems that I am finding decriptions of certain plants that say "improved version of such and such........" yet the plant was not called a hybrid to begin with. I wish I had a source to show an example of this, but I would have to look something up (it is late). Are there many plants offered that are hybrids but it does not specify in the description? It seems that being a hybrid would be something important to know, and at the same time it would seem necessary to mention, as someone out there produced that hybrid and deserves recognition for it. Once something is hybridized, does the person who developed it have to "patent" it so that no one else can claim it, or does this not happen when it comes to plants??

Obviously, I need to do some research on this, but you guys make it so easy to get a "quickie" lesson when I get curious about something!

A plant can also be reproduced from a cutting ... since all parts of a plant are not identical I suppose one could make a cutting from the desirable part of the plant and propagate it as a clone ... the genetics would not change ...

Good Day ...

"Improved" could mean some sort of cross was involved. That's one way to go about "improving" a variety. Sometimes the improved version is grown out a few generations to try and stabilize the cross and then released for sale, and sometimes not. It depends on the cross and by implication the parents in the cross. Another way is when you have a mutation (spontaneous or otherwise) that produces something interesting. This mutation may occur in the fertilisation stage, in which case the seed carry the mutation or it could happen on a growing part of the plant. These "mutant" branches are called sports. They may produce flowers then seed which you could propagate or you could propagate the branch itself - this is how new colour variations in bougainvilleas are multiplied since they don't produce seed all that often.
As for patents, this varies from country to country. In Australia you cannot patent a hybrid but you can obtain breeder's rights, which gives you rights over its sale and distribution - rather like copyrighting a song. You can however patent a genetically modified organism - but that's a whole different ballgame! I think US laws are very similar.
Hope this helps.

I imagine commercial breeders generally get whatever patent protection is available in their country. Another source of protection is just keeping the parent varieties secret. Below is a link to a discussion on the Heirloom forum (why there?) about the parentage of the Big Boy Hybrid Tomato. It helps to have something like 3000 different varieties of tomato.

It's even harder for someone to duplicate your work if one or both of the parent varieties was developed by you.

Here is a link that might be useful: Big Boy Tomato Parents?

There are different kinds of hybrid. F1 Hybrids are produced by inbreeding 2 or more lines or strains, then crossing among them to get seeds that will produce a uniform and vigorous population. This is commonly done with corn. Sometimes a double-cross is used: four inbred strains are crossed (AxB) x (CxD) to give plants that are not quite as uniform as a simple F1 Hybrid, but still vigorous and maybe a little more adaptable to varying conditions.

Species hybrids, on the other hand, are usually less uniform but often more vigorous than the parents. The second (F2) generation is commonly very variable, but often even more interesting than the first generation. The plants are still hybrid in the sense that they retain characteristics of the parental species.

In Roses, for example, we may cross a reblooming China rose with a cluster-flowered species (Multiflora, Moschata, Wichuraiana). The F1 progeny are usually pink flowered ramblers, but in the F2 we may expect reblooming cluster-flowered types.

The idea that seeds from hybrids are worthless was originated as a marketing tool -- to persuade people to buy new seeds every year. When new traits became available, like the pure yellow tomato, it was offered only in F1 Hybrid seed. Marketing tricks aside, it is perfectly possible to raise good quality seedlings from hybrid plants. We just have to be willing to save the best plants and discard the rest. And if we care to make the effort, we can develop a new strain of our own.

Karl

Here is a link that might be useful: Bulb 'n' Rose