In a world with different skin, hair, noses, and just appearance in general, Racism is a big part of it. People in every ethnic background make racist statements about each other, such as blacks to white and Hispanics to blacks, so on and so forth. Racism is not even a word; Human kind has invented this even though all these ethnic groups are from the same species-Homo sapiens. This is a reasonable statement which the majority of the world has not even stopped to consider.
The word Racism started to make its first manifestation in the early twentieth century but the idea that a certain group of people are superiors than other has been around in the word for an extensive time. For example in 15 century and 16 century the African populations were considered to be lower than any race and the Europeans use them as slaves.  Even before that when the Egyptians use the Jewish population as slaves to help them build their famous pyramids with their hard unpaid manual labor. In the late twentieth century when the United States start to segregate other nations around the world still had the same crisis. One of the worst racist events against any ethnic group situated in Europe to be accurate in Germany beneath the command of Hitler; slaughtering millions of Jews, Gypsies,Â andÂ Catholics.
Effects of racism against ethnic groups can cause many social and political conflicts. In some cases this actions have even brought the ethnic groups to be paid lower than others of different societies because of their religion, appearance or nationalities. They're even put to do higher risk jobs because no one else would.  In example like the Immigrants that pass through a journey to get to the United States to get a healthier life, they have to work with being paid small quantities of money for a high risk or Unpleasant job that the citizen of the country are unwilling to do. Racism brings harms to others physically or emotionally in many ways: Self hate can be causes of racism were the person might dislike for his/her qualities. Suicides also are affected by racism, if their constantly mocked this can lead to depressions, suicidal thoughts and then death. Racial problems may also cause ethnic groups attack against someone or another certain ethnic group they consider worthless or bellow themselves. Some even develop eating disorder because of verbal abuse that has affected him/her. Others take the anger and frustration becoming bullies and racist themselves. These thing help develop Ethnic hatred between each other and discrimination arise from these events.
Racism has multiple concepts; Many types of racism. Racism has a cause and effect. Discrimination, oppression, violence, intimidation are some of them. While racism between races are able to happened because of their difference in cultural, heritage, language, ideas and historical factors. Individual racism is an intentional n the part of the perpetrator to injure or harm another because of perceived racial difference.  The lynching of blacks by KKK is an example of individual racism. Institutional racism evolves when racial oppression and inequality are at the norm in a society those attitudes subsequently permeate the various legal, educational, and economic institution, creating a system that directly or indirectly excludes or discriminates against, members of one or another racial or ethnic community. 
Nativism occurs rather a lot in the United States, as thousands of people migrate every single year hoping for better standards of living for them and their families. As more and more they come and fill up the American cities with their religion, language, and ideas, Citizens complain on how their presence is taking jobs away that belong to them, they start becoming xenophobic and start to hate the immigrants.  This starts to cause ethnic tensions and hate groups develop against these foreigners.
Moving on to a specific event in history, the most dreadful forÂ the UnitedÂ States is the initiation of the organization Ku Klux Klan (KKK). KKK is a white ethnic group against the Immigrant population in the United States. Black African Americans aren't the only ones affected by the KKK like some may think but also Catholics, Jewish and other religions that aren't protestant.  The clan is made up of White supremacists. In the1890s African Americans where described as belonging to a diseased, degenerate race that it's not likely to survive more than a generation. Â This so called disease is known as "Nigra" . The MississippiÂ Senator James K. Vardaman foreshadowed that Nigra would be over by the 1920s.  The African American populations slowly increase as beatings and killing slowly came to a decrease. When they realized that the senator of Mississippi had an incorrect hypothesis the Ku Klux Klan decided to take action. They started atrocious acts such as murders against black political leaders, church leaders and community groups. They even also drove black farmers of their land with their assaults and hatred acts of violence. They publicized the death of each African American weekly. The KKK also in an act to intimidate started burning the Christian cross. In 1924 the organizations reached a peak of four million members but slowly decrease to the hundred thousand in 1930s and faded away in the 1940s. 
When the North union army won the Civil war, the United States ratified the thirteenth amendment and slavery became dissolved. Southern states worked quickly to establish Black codes. Black code is design to prevent blacks from obtaining full rights; they could only marry, own property, negotiate contracts, and have limited participation in court proceedings against other blacks. 
As African Americans lost tolerance with segregation during the World War II. A black Labor leader Philip Randolph went to Washington D.C. to object the prohibiting from employment in the industries to blacks. His protest was victorious; they established the Fair Employment Practices Committee. During the war years blacks generally saw an enhancement in their standard of living and laid the groundwork for the civil rights movement of the 1950s. After Blacks in the military were approved, the Black African population in the United States still had a bumpy moment particularly in the military when World War II began. Several riots started in the army as a situation that happened when execution of a black soldier at Fort Benning, Georgia, in 1941. Another riot started in Cap Stewart, Georgia where the military police clashed with black soldiers protesting segregation in facilities and racial prejudice in close by towns.
After the Japanese attacks on Pearl Harbor, President Roosevelt signed an executive ordering Japanese Americans living in California, Oregon, and Washington to reassign to custody camps for the enduring of the war for their wellbeing. The detestation acts compel them to go incognito which affect the United States in the loss of 2/3 of their Vegetable crops which the Japanese Americans cultivate in the west coast.  Within days of the Pearl Harbor attack Japanese were fired from Civil Service jobs, their medical license and law were revoked, their business were Boycotted and their insurance policies were disregarded.  Japanese American got treated like prisoners in their own country just because of their background. Families were housed in the horse stalls before being shift into camps in inaccessible areas in Arizona, Arkansas, California, Colorado, Idaho, Utah and Wyoming.  Their farms, homes, business, and back accounts were confiscated. Some children often exploded in fury, some refusing to sign a loyalty oath and renounce to their American citizenship, others volunteered to serve in the U.S army but were segregated.
Military riot were nothing compared to riot in cities, such as one that occurred Detroit in summer of 1943.  Young Black and white kids got involved in a small fight at a jam-packed beach in Detroit. In hours about five thousand people rioting. The rebellion got out of control for three days over huge parts of Detroit. The president had to announce state of emergency and called in about five to six thousand National Guard troops for aid. About thirty blacks were murdered and ten white people also murdered; about eight hundred people wounded. 
In some countries there are some laws that prohibit discrimination based on race or appearance.  Most apply to federal government base industries. Hate crimes "Racism" are considered criminal act in many countries. Definitely standing up for the Anti-Racism is the best thing that anyone can do. Even though we all come from different cultures, we are Homo sapiens that live all together in this world. In a world with no racial tension and ethnic hatred we be a near to perfect world.