What is the difference between normal plants and weeds?

Question

I have no idea what it is. Please help. Thanks.

Answer 1

Weeds do something nasty. What it is varies, but common weeds come up uninvited in disturbed land, especially gardens or cropland,  spread, and are hard to get rid of. Some plants spread so much they crowd out other plants. A few have a bit of extra nastyness, like thorns or poison.

Answer 2

A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-made settings such as gardens, lawns or agricultural areas, but also in parks, woods and other natural areas. More specifically, the term is often used to describe native or nonnative plants that grow and reproduce aggressively.

Weeds may be unwanted because they are unsightly, or they limit the growth of other plants by blocking light or using up nutrients from the soil. They also can harbor and spread plant pathogens that can infect and degrade the quality of crop or horticultural plants. Weeds may be a nuisance because they have thorns or prickles, cause skin irritation when contacted, or parts of the plants might come off and attach to fur or clothes.