Weeds are plants that are growing where they're not wanted. They out-compete other plants for nutrients and can spoil the look of your garden. Weeds can take any form and can vary depending on where they grow.
There are a number of measures you can take to prevent weeds from taking hold in your own garden and beds and pathways:
Keep lawns in good condition. Remove seed heads from weeds. Take care when bringing soil or equipment into the garden. A layer of mulch will smother weeds and prevent their germination in the soil.
The more you know about weeds, the better your chances are for controlling them. For more information on controlling weeds in garden beds and pathways, watch this video gardening tutorial.