Here's an overview of the IELTS General Writing Task: Part 1: 

Format:
In this task, you will be presented with a situation and asked to write a letter in response. There are three types of letters you might be asked to write:

Formal Letter: You might be asked to write a letter to an authority figure, a company, or a formal organization. This could include letters of complaint, job application letters, or letters requesting information.
Semi-Formal Letter: This type of letter is written to someone you know but not intimately. It could be a colleague, a neighbor, or a friend you don't have a close relationship with.
Informal Letter: Informal letters are written to friends, family members, or people you have a close relationship with. These letters have a more relaxed tone.

Word Count:
The recommended word count for the IELTS Part 1 General Training Writing test is usually around 150 words. It's important to adhere to the word count guidelines, as writing significantly more or less than the suggested word count could affect your score.

Task Types:
The content of the letter will depend on the type of letter you're asked to write. The prompts might include:

Situational Task: You'll be given a scenario and asked to write a letter responding to the situation. This could include requesting information, making a complaint, or applying for a job.
Expressing Thanks: You might be asked to write a letter thanking someone for a gift, an invitation, or an experience.
Invitation: You could be prompted to write a letter inviting someone to an event or occasion.

Assessment Criteria:
Your letter will be evaluated based on several criteria:

Task Achievement: How well you address the purpose of the letter and respond to the prompt.
Coherence and Cohesion: The organization and structure of your letter, including the logical flow of ideas and the use of appropriate formatting.
Lexical Resource: Your vocabulary range, accuracy, and the variety of words and phrases you use.
Grammatical Range and Accuracy: Your use of grammar, sentence structure, and the variety of sentence types.

Tips for Success:
Here are some tips to help you succeed in the IELTS Part 1 General Training Writing test:

Read the Prompt Carefully: Make sure you understand the type of letter you're being asked to write and the specific requirements.
Use Appropriate Tone and Language: Match the tone of your letter to the situation. Use formal language for formal letters and a more relaxed tone for informal ones.
Organize Your Letter: Structure your letter with a clear opening, body paragraphs, and a closing.
Address All Points: Ensure you address all the points mentioned in the prompt.
Practice Writing Different Types of Letters: Familiarize yourself with the different types of letters you might be asked to write and practice each one.
Proofread: Leave some time at the end to review and correct any errors in grammar, spelling, or punctuation.

Remember that consistent practice and exposure to different letter-writing scenarios will help you become more comfortable and proficient in this task. We have given you some Part 1 example questions here.