There are a lot of reasons for Britain to colonize other countries.
Industrialization
The sudden rise in demand, introduction to new technology like harvesting machines and steam power gave rise to industrialization. This increased the production 10 times.
To meet the rise in demand England needed resources. To attain these resources England started making colonies.
World Market
The production was so tremendous that it was now termed as surplus. To sell the surplus produce markets were necessary. Thus, England started colonizing other areas to gain markets and sell their products.
Political Motive
It was just like a war between England and France and other European nations. To make an impressive and strong political nation they wanted more and more land.It was just like a competition.
Rise in Population
The introduction of advanced medical services steeped down the death rate. The population was increasing at a fast pace. To give land to the ever increasing population colonizations was followed.
There is a lot of debate about colonization and its positive and negative effects. I can put forward two faces of the debate-
Development
It can be learned that the countries England colonized were economically and educationally backward as compared to England itself. For ex- India at that time was educationally backward. But the Britishers introduce education in India though they wanted to educate people so that they could find easy employees who would be ready to work at low wages in military and civil services. They introduced law which formed the basis of the current law system of India. In countries like America, they boosted the technological advancements 5 times the previous. They tried to improve the society and eradicate evils out of it like child marriage and dowry system. They helped low caste people who were ill-treated in their states, convert to Christianity and enjoy a life of dignity.
Unfair Methods
But their methods were always unfair. They used policies like Divide and Rule. To gain control over the colony they used force and inhuman activities. Thousands of innocent people were killed many times. Their policies always focused on how they could gain more and more profit. For ex- they smuggled opium to China.
could gain more and more profit.
Destruction:Economically
They destroyed the local business rapidly. Industries were shattered as European goods were cheap and good in quality. This made the lives of local people miserable. They destroyed handcraft business as hand made goods were costly as compared to machine made goods.
Apartheid
They initiated apartheid in South Africa. Thankfully apartheid is not a problem now because of Nelson Mandela.