Every carpet manufacturer states that care and maintenance of their carpet STARTS with proper and frequent vacuuming.  This is the most important step to keeping your carpet clean.

Carpeted surfaces are better than bare floor for allergy sufferers or asthma sufferers.

Check out this link from CRI.

Properly vacuumed carpet actually helps improve your indoor air quality.

Carpet actually acts an air purifier, by capturing particles that are constantly falling.

You need to clean the “filter” (your carpet), regularly.

Check out this link from CRI

Proper vacuuming techniques are vital to removing as much loose debris as possible. When you vacuum, try not to vacuum toooo quickly.  Slow down. 

You should try and vacuum in multiple directions to remove as much dirt as possible.  Using a North, then South, then East, then West directionality will help get the carpet fibers to stand up properly and remove the soil from between the fibers.