(Continuing the series of posts that I started two months ago...)
Conjunctions are the words used to connect two words, sentences or clauses. They are these small knots in a sentence that keeps it together. Sadly, these conjunctions can be added to make sentences longer than what the reader's mind can capture. (Imagine someone saying, "I did this because I wanted to get this and this but she said that I should do this or else I will have to face this or this or this and yet not be able to achieve this.") It is conjunctions that allow such difficult to understand sentences - faltering the basic goal of communication.
Conjunctions, however, are the 'junctions' where two sentences meet. (That perhaps could be the reason why they are called so.) Conjunctions create relationships between them. Relationships of common goal (I did this and he was with me.), uncommon goal (I did this but he was not with me.) or other relationships in terms of conditions (If I do this, he will be with me.).
Conjunctions are relationships between sentences... Relationships of goal, of reason, of condition, of dependence. Conjunctions truly set up relationships. They are the ones that help a group of sentences become a paragraph.
Relationships add meaning. So do conjunctions.