Search/replace groups using sed

This is the most common way of my sed usage:

echo Good morning | sed 's/\(.*\s\+\).*/\1evening/g'

Here are brief notes on that ..

The above script changes Good morning to Good evening. Note that the following characters needed the escape character \:

• Brackets to create regex groups: \( \)
• Plus sign to match one or more times: \+
• Note that the . and * characters don’t need escaping.