What is internal and external validity?

Part 1:

Based on the course readings and research, in a minimum of 300–400 words, post your responses to the following:

• What is internal and external validity? When conducting research, why is there often a trade-off between internal and external validity?
• Is there a benefit in achieving a high level of one type of validity (internal versus external) over the other? Is there a way to design a study or series of studies to have high internal as well as high external validity? What would be the benefit?