If it's a stranger on the street, we hate it. Don't touch us. Don't even get close to us. Just about all girls hate this because we see it as one of a few ways, one being danger, two being objectification, three being just blatant disrespect. We take it very personally.
If it's flirting, then it depends on the girl's mindset and intentions. Does she want to manipulate you? Girls that touch with an "innuendo", such as grabbing your thigh before the dating phase or putting their hands on your neck, either want money or sex. Or a favor. Girls like this are usually VERY good at it too. To be honest, they don't even like it, they just love to see your respond by being at their beck and call.
If it's innocent flirting, we get excited, as we feel a new relationship could be budding. For instance, my LT boyfriend and I first met while volunteering at a hospital. Sometimes we were receptionists, so when nobody was looking we would fling each other's chairs into each other and corner them into the long desk crevice. (The desks were built in like at a hotel) Afterwards, when it was late at night, we would cuddle as we got more and more tired. That's innocent touching, and it brought us much closer together. Women know this and it increases our trust!
In the dating phase, women are funny when it comes to touching. Many of us are unclear about how long we should make a guy wait for sex. We know that, even if we do like you, we have to withhold because we want more than just a friend with benefits- we want someone to be with in a relationship. We think that if we dive into sex too soon, or even some types of touching, we'll be a "whore" in your book. Men don't typically want to settle down with a whore, so opening up to someone too soon can end the relationship. To deal with this, women often work in increments. Touching, kissing, and sex all come after a set number of dates. The longer you wait, the more we feel like you care about us. This causes us to trust you more, especially since at this point we would really start getting to know you. After the trust comes, then we're more lenient with touch.
If it's the man we love, then we can't go back home fulfilled unless we've been wrapped up together all night- it doesn't even have to be sexual. It can just be an hour of cuddling and caressing. Women love to touch the man we're committed too. It's our duty to shower the man we love with everything he could ever want when it comes to love, affection, and just care overall. When it gets to this point, women can obsess over making their partner happy- which is why many women become housewives as they want to devote their lives to taking care of the family. It's a natural feeling for us that almost entirely stems from touch and the trust that it brings!
I hope I could give you a female perspective! Good luck in all your romantic endeavors!