What are connectors?
 Connectors, markers or linkers are all words that describe the linking words or phrases that are used in a text to organize ideas and to help the reader understand the text better.  In fact, they are like the glue that sticks sentences together. Linkers hold the text together as a unity as they connect sentences and make the transition between sentences and paragraphs less abrupt and, therefore, easier to follow. A piece of academic writing without connectors may resemble a shopping list in which ideas are placed one after the other but no relation is established between those ideas, which is left to the reader’s understanding. 
Why should I use connectors?
 Connectors are like signposts that lead the reader throughout a text and help him to understand a text better. From the writer’s point of view, they help to organize ideas. At university level your tutors expect you to use a wide range of markers.
How many types of connectors are there?

There are many different types of connectors depending on the meaning they convey.  There are connectors that are used to add ideas (addition markers), others show contrast between ideas (contrast markers) and some others show one idea is the logical consequence of a previously mentioned idea (consecutive markers). This is a basic classification.  Below you will find examples many other connectors, their meaning and uses.

  • Adding a point

as well as, in addition to, not only … but also

  • Developing a point

besides, furthermore, in addition, indeed, moreover, what’s more, on top of that, to make matters worse, in fact, as a matter of fact.

  • Explaining a point

to put it another way

  • Contrast

However, nevertheless, all the same, although, while, even though, despite the faact that,none the less, on the contrary, on the one hand, on the other hand, as opposed to, whereas,  in contrast

  • Explaining reasons

As a result, accordingly, thus, hence, consequently, for that reason, in turn, owing to

  • Making generalizations

broadly speaking, generally speaking, on the whole, by and large, to a large/ some/ certain extent.

  • Starting

For a start, first of all,in the first place, for one thing, to start with

  • Giving new information

incidentally, by the way,

  • Concession/qualification

even so, all the same, anyway, at any reate, having said that, even so, all the same, at least

  • Giving a personal opinion

To be (perfectly) honest, to tell you the truth

How do I know which connector I have to use?
 The choice of connector depends on the purpose of your sentence.  You should ask yourself “Am I expressing an opinion?”  “Does this sentence involve a generalization?” “Am I adding a new point in favour or against an issue?”   You should ask yourself these and many other questions.    Your answer will determine if one linker or other will be necessary. 
How many connectors do I have to use in a text?
 There are no written rules as to how many connectors to use in a text.  However, you should find a balance between sentences with and without connectors. Go through your assignment once it is completed and try to see if it asks for a few more or a few less linkers.  You can also ask a friend to go through it for you.   Using too many connectors can be as bad as not using any at all, as it can slow down the pace of the text or even make it difficult to understand.