They stick the tip on with glue, blend it in with a file, paint it over with the gel and set it under a uv light.
I think they are less damaging to your real nails but they're not as strong as acrylics.
oooo I love gel nails both to do and to have done. em is correct that the gel is cured under uv light. They are not as strong but are kinder to nails and no chemical smell which i love as I have kiddies and do my own. the gel also comes in colour form.
gel nails are great, although better for your nails than acrilyic, still leaves them in pretty poor condition when they are removed (had mine removed in march and they've still not got back to full strength, so off to get them reapllied on friday)
but imo they look great i have the pink gel, because it supposedly looks more natural, need to have them done every 2-3 weeks and maintenence can be a pain. i borught a kit from argos for £50 which if i was a braver woman i could do the whole set myself with but just use it for repairs as they cost £5 a time at the salon i go to.