For e-mail, websites, and any communication which is viewed on a screen, one space is best. The screen usually creates enough space with one, due to the use of pixels. Also there are technical reasons with html that make one space better.
If your writing is going to be viewed in print, such as magazines or brochures, two spaces is better. One space does not provide enough visual space on a printed page, especially with small type. Letters are typically spaced closer together on a printed page (the higher resolution allows more accurate spacing), so the need for a visual break between sentences is more important.
For e-mail, websites, and any communication which is viewed on a screen, one space is best. The screen usually creates enough space with one, due to the use of pixels. Also there are technical reasons with html that make one space better.
If your writing is going to be viewed in print, such as magazines or brochures, two spaces is better. One space does not provide enough visual space on a printed page, especially with small type. Letters are typically spaced closer together on a printed page (the higher resolution allows more accurate spacing), so the need for a visual break between sentences is more important.