"Were you taught to put two spaces after a period at the end of a sentence? Many people were, but now most publications recommend using just one." - Mignon Fogarty, the Grammar Girl
Proofed's Insight: In her article, "Two Spaces after a Period", Mignon Fogarty provides interesting background history on the movement away from two spaces after a period at the end of a sentence. However, note, not all editing styles have adopted the change from two spaces to one after a period.