Copyright in a photograph is normally held by the photographer. However, if he takes the photograph in the course of his employment, copyright will be held by the employer.
In general, a copyright owner has the right to show a photograph when and where he likes (including by publication in print or by placing it on a website) and to distribute it to whomever he likes. (There are, of course, legal restrictions relating to such things as official secrets and pornography but your question makes it clear that you're not asking about such matters).
Where an image is used for commercial purposes, photographers are advised to obtain a signed 'model release form' from people who appear as individuals (rather than, say, as a member of a crowd) in their pictures. This is because such people may have the legal right to prohibit the use of their image or to receive payment for such use. (In general, this doesn't normally have much to do with 'the man in the street'. It's primarily to stop advertisers from using an image of, say, Tony Blair or Andrew Flintoff, in their promotions, without permission).
In some circumstances, it can be argued that when a photograph is taken on private property, the owner of that property either owns the copyright or has the right to control publication and distribution. (This normally applies, say, to photographs taken in stately homes or within commercial premises. It's unlikely that, say, a woman who allowed her boyfriend to take her photograph in her own home, could exercise any legal rights over the image, unless he sought to use it for commercial purposes).
If we put aside some of the specific restrictions mentioned above, a photographer normally holds the copyright in a photograph and has the right to distribute it. For example, If I stand on the public footpath and take a photograph of you in your garden, I have every right to show that photograph to anyone I choose and