What are weeds? Why should they be removed?

Dear student,

Weeds are the undesirable or unwanted pants growing along with the crop plants. 
Weeds should be removed in early stages of crop growth because:
They compete with the planted crop for air, space, sunlight, nutrient, water and make them deficient for the main crop. They quickly adapt to the environment and affect the growth of the crop.
Methods to remove the weeds:
1. Can be removed manually by hand picking them.
2. Spraying weedicides which kill the weeds.
3. Using implements like hoe, trowel.

Regards