Article V of the United States Constitution is very short and to the point. The language is clear and concise. There is only one section -- a single paragraph describing the ways in which the document can be amended. It also includes a brief mention of when it can be amended and what it takes for a state to be excluded from the voting on an amendment to the Constitution. As articles go, it is one of the simplest and least controversial.
Go here to see the full text of Article V.
The majority of Article V describes voting processes for adoption and ratification of an amendment, thus cementing the fact that changing the U.S. Constitution by adding to it is permissible. As it pertains to adoption, there are two accepted methods. Firstly, a two-thirds majority from the House of Representative and the Senate is sufficient. Alternatively, two-thirds (now 34/50) of the states can call for a national convention.
Ratification of an amendment is entirely up to the states. Three-quarters (now 38/50) of the states must ratify or have state conventions that result in support of the amendment. In most cases, the U.S. has used the former to ratify amendments, but there was one instance of state conventions ratifying an amendment. That was for the 21st Amendment, which was also unique in that it repealed a previous amendment.
The end of Article V states that there could be no amendments before 1808, which is the most controversial part of the article. It also asserts that no state can lose its voting right in regard to amendments without first consenting to the loss.