I think the original purpose of toner was to tighten the skin through the application of alcohols. Alcohols are drying because they evaporate easily, taking water from the surface of the skin. When the skin is dry, it becomes tight (as we all know!).
As skin care has evolved, there are more toners that include many other ingredients without alcohol. I love my toner, but only use an alcohol free one. I hate the way they make my skin feel when they have alcohol. If you have even moderately dry skin or sensitive skin, I would encourage you to stay away from them. They actually make your skin oiler (in most cases) because they dry you out and your skin produces more oil to compensate for the loss.
Oil is there to protect your skin, so you dont want to get rid of all of it. The more you get rid of it, the more it will produce. I have suffered from bad acne my whole life and have been through every product and medication you can think of. I have finally controlled my skin extremely well in my adulthood by not being so mean to it. I remember I used to scrub my face in the shower with Clinque's 3 step system (the bar of soap and a face cloth). I just cringe thinking about it now. Then I would get out and wipe their alcohol laiden toner all over my face and try to compensate with the lack lustre Dramatically Different cream. Stupid, stupid, stupid. Now, I dont even use a face wash (unless I wear heavy makeup). I use Proactive's wash periodically (probably every 2nd day) and alternate with an at home microdermabraision kit. I use the proactive toner (which has a minute amount of alcohol). I moisturize very well and my skin has never been clearer.
I guess what I am trying to say is just be careful with your skin. I regret all the things I did because I thought I was supposed to do it. I thought I was supposed to scrub the livin daylights outta my skin because it would make my acne go away. I have premature wrinkles from all the creams, medications and drying things I used. I know alcohol based toners are not the only reason I have them, but it definitely contributed to my skin problem.
In all honesty, I really think the less you put on your skin, the more your skin will thank you for it.
HTH!
- sorry about the tangent!