Unlike his unanimously-elected predecessor, George Washington, John Adams was a member of the largest political party of his day - the Federalists.
The Federalist party believed in a strong federal government, a protective tariff, a strong national bank, and opposed the ideological implications of the French Revolution. These views opposed those held by the Democratic-Republicans (often known as Jeffersonian Republicans, after its most well-known member, Thomas Jefferson).
John Adams had always been known as a man who, while perhaps coming across as a bit sour and gruff, was a truly patriotic American and a person of great personal integrity (one of the only early presidents never to have owned a slave). His early claims to fame include publically opposing the Stamp Act of 1765 as an expert in English Constitutional law.
In addition, Adams earned notoriety (and controversy) by defending the British soldiers after the Boston Massacre as a Massachusettes lawyer (because in his view, everyone has a right to defense).
In addition, Adams helped his friend (and later political adversary) Thomas Jefferson to draft the Declaration of Independence as a member of the first continental congress, and then served as the American ambassador to France in the years leading up to and during the war of American Independence, helping achieve funding for the war throughout Europe.
After the war, he was named the first American minister to England in 1885.
Throughout this entire period of his life, Adams remained true to the Federalist cause - recognizing the importance not only of freedom from Britain, but in national strength and unity among all the states.
Like fellow federalists Alexander Hamilton and John Jay, John Adams was a staunch defender in the new constitution, believing that the only way to achieve a successful government structure was by an experimental mixture of democracy and republicanism - that is, the division of government between federal and state governments, with the state governments being the more "democratic" of the two.
In the first presidential election of 1898, John Adams came in second in the electoral college, and was thus named America's first Vice-President - a position which caused him to remark that, "My country has in its wisdom contrived for me the most insignificant office that ever the invention of man contrived or his imagination conceived."
Nevertheless, as Vice President, Adams was able to do some good, serving as President of the Senate and casting 29 tie-breaking votes, earning for himself enough respect to be chosen as successor to President Washington.
References:
McCollough, David. "John Adams." Simon & Schuster. 2001.
"Biogaphy of John Adams." The Whte House. www.whitehouse.gov/history/presidents/ja2.html