Basics of Prompting

Basic Prompts

You can achieve a lot with simple prompts, but the quality of results depends on how much information you provide it and how well-crafted it is. A prompt can contain information like the instruction or question you are passing to the model and including other details such as context, inputs, or examples. You can use these elements to instruct the model better and as a result get better results.

Let's get started by going over a basic example of a simple prompt:

Prompt

The sky is

Output:

blue

The sky is blue on a clear day. On a cloudy day, the sky may be gray or white.

As you can see, the language model outputs a continuation of strings that make sense give the context "The sky is". The output might be unexpected or far from the task we want to accomplish.

This basic example also highlights the necessity to provide more context or instructions on what specifically we want to achieve.

Let's try to improve it a bit:

Prompt:

Complete the sentence: 

The sky is

Output:

so  beautiful today.

Is that better? Well, we told the model to complete the sentence so the result looks a lot better as it follows exactly what we told it to do ("complete the sentence"). This approach of designing optimal prompts to instruct the model to perform a task is what's referred to as prompt engineering.

The example above is a basic illustration of what's possible with LLMs today. Today's LLMs are able to perform all kinds of advanced tasks that range from text summarization to mathematical reasoning to code generation.

Prompt Formatting

We have tried a very simple prompt above. A standard prompt has the following format:

<Question>?

or

<Instruction>

This can be formatted into a question answering (QA) format, which is standard in a lot of QA datasets, as follows:

Q: <Question>?
A: 

When prompting like the above, it's also referred to as zero-shot prompting, i.e., you are directly prompting the model for a response without any examples or demonstrations about the task you want it to achieve. Some large language models do have the ability to perform zero-shot prompting but it depends on the complexity and knowledge of the task at hand.

Given the standard format above, one popular and effective technique to prompting is referred to as few-shot prompting where we provide exemplars (i.e., demonstrations). Few-shot prompts can be formatted as follows:

<Question>?
<Answer>

<Question>?
<Answer>

<Question>?
<Answer>

<Question>?

The QA format version would look like this:

Q: <Question>?
A: <Answer>

Q: <Question>?
A: <Answer>

Q: <Question>?
A: <Answer>

Q: <Question>?
A:

Keep in mind that it's not required to use QA format. The prompt format depends on the task at hand. For instance, you can perform a simple classification task and give exemplars that demonstrate the task as follows:

Prompt:

This is awesome! // Positive
This is bad! // Negative
Wow that movie was rad! // Positive
What a horrible show! //

Output:

Negative

Few-shot prompts enable in-context learning which is the ability of language models to learn tasks given a few demonstrations.