Keep your outdoor tomatoes developing and ripening longer by 'stopping' the growth above the last trusses.
The reason for pinching out the tip or 'stopping' on outdoor tomatoes, is there comes a point in the growing season of tomato plants - especially when growing outdoors - where there is not enough time left for them to produce and ripen more fruit before the Autumn season stops them growing further. At the latter part of the season, there is a lot of energy put into producing growth of the leaves and stems, which are wasted. This energy is far more beneficial if we can direct it at what we want from the plant. More and better tomato fruits.The way to divert this excess energy into the tomato fruits with outdoor grown tomatoes, is by stopping the excess growth of foliage above four or five trusses of tomato fruits on the stem. That is to say, you pinch out the growing tip to stop and additional upwards growth. If you live in warmer lighter districts, then you can allow five trusses to develop. If you live in colder areas, then usually three of four maximum. Your remaining fruits will develop and ripen better as they soak up the added energy supply that is available to them after pinching out the growing point..
Stopping the outdoor grown tomato plants simply involves nipping the main shoot out directly above the last truss that you want. (Three, four or maybe five trusses of fruit. Then all of the energy produced by the plant, and the feeding that you should be doing, will be diverted into developing the fruits - not wasted leaves. this can be done as early as July if the plant has developed well, or August if it is a little slower. Stopping the tomato by pinching out the tip later than August does not normally have any beneficial effect.
Once you 'stop' your tomatoes by pinching out the growing tip, it may well be that there will be increased side shoot growth. So take these out on a daily basis - unless they are bush tomatoes.
There is no need to stop bush varieties of tomatoes. They do it themselves by their habit of growth. These are normally grown outdoors and not in the greenhouse.
If you are growing your tomatoes in a greenhouse, then it is normal to have seven or eight trusses, for they will continue to develop and ripen well into the Autumn season. They will not need to be pinched out until after that.
That's really all there is about stopping tomato plants that grow outside!