In your city, town or village you must have seen trains run by on tracks with an engine in front and many compartments behind. You would have seen at the station an engine being separated from the compartments and joining with another set of compartments. There is a message in this for our English classes - conjunctions are very similar to trains!
Conjunctions are also called joining words and they perform the task of joining words or sentences together. Just as many compartments are joined to one another through a coupling mechanism so also we join words or sentences through conjunctions - they are joining words.
Take a look at these two sentences:
"She stood up AND waited to see what he wanted."
"He lost his money in gambling, BUT he still seems to live comfortably."