OK, you activate a summit when you have just 1 contact from the summit (or within 25 vertical metres of it - this is called the activation zone and is there as people have a tendancy to build things on summits (radar stations, Churches, hotels etc. etc. so getting to the exact summit is not always possible).
Activating and qualifying a summit are two different things - to quailfy a summit you need a minimum of 4 contacts with different stations and then you receive your activator points.
If you happen to contact another SOTA activator while you are on the summit - that is a Summit-to-summit or S2S contact. I counts in your total of the number of contacts you have made from the summit but it also gives you chaser points for the other summit AND S2S points for BOTH summits (this something I only just found out).
So lets saty you qualify a 1 point summit and have a contact with someone on a 3 point summit, once you enter your log you will have:
1 activator point
3 chaser points
4 S2S points.
The way that the databases GUI interface works, you enter your activator log in the activator log screens, then you go into the chaser logs system and enter the S2S contact, remembering to check that it is an S2S contact and then it asks you for your summit code.
If you use one of the many PC or Smart phone logging programs, these will produce a CSV (spreadsheet data type) file which when uploaded to the SOTA database, takes care or activator entry and S2S entry (which in the background also updates your chaser totals).
So you see getting one (or more) S2S contacts from a summit, soon pushes up all of your scores.
By the way although 4 contacts from a summit is the minimum to get the activator points for the summit, you can work as many other stations as you like - unless they are ther summits, you wont get any more points for them, but you are giving out the points from your summit to the chasers.