Is it required? How would it be different from a resume or CV?

Actually I required a simple letter but professional one, like I have moved to this new employer.

I would make the letter short and snappy, and include several points from your CV that highlight that you are a valuable employee and will do your best to bring success to the company.

An introduction letter is eactly how it sounds. Introduce yourself. Pull from your resume & CV (as stated by Wondergirl) to include reasons you are competent and beneficial to your employer. They don't need life history, family background etc... kepp it at a proessional level and keep the introduction short and sweet and focus on your employment, not your life.

Pretty much put your resume & CV into full words. :)

Here's a letter to introduce a new employee to a company (brighthub.com). Perhaps you can use it as a guide and rewrite it in the first person ("I") to fit your situation (see my example after the sample letter).

Dear Davis Industries Family (or Employees):

Please join me in welcoming Douglas Wilkinson as our newest team member. Doug is taking on the Development Coordinator position as of March 4. He will be overseeing the upcoming marketing development planning committee and has some exciting ideas regarding a television campaign that can take Davis Industries to the national level. Doug reports to Jim Medina and will work in tandem with Bev Fuller. Laurie Rowe will be Doug's assistant on an as-needed basis.

Doug comes to us from Allied Warehousing in Duncanville, where he was Business Development Project Specialist. In this position, he identified opportunities for improvement, made constructive suggestions for change and helped brainstorm solutions. He has a Bachelor's degree in business as well. In addition, Doug played outfield for the Duncanville Church of Christ's baseball team and is looking forward to trying out for the company team.

There will be an informal staff lunch in the conference room at 12:30 on March 4. Please come and introduce yourself. Pizza and soft drinks will be provided. If you are not able to attend, stop by Doug's office any time next week. He will be on the second floor in the currently vacant office across from the client meeting room. Doug's extension will be 207 and his email address is d.xyz AT davisind.biz, so be sure to update your contacts list.

Thank you for showing our newest team member the ropes.

Warmest Regards,

Darrin Davis, CEO

For instance --

Dear Oak Brook Library staff:

As of January 3rd, it will become my great pleasure to join your team and have the responsibility of cataloging all of the new non-fiction books as well as the AV materials. In addition, I will be coordinating the court-ordered community service program and also the patron volunteer program. At my previous work site, I was in charge of a successful writers' group that met twice a month and hope to start such a group in this community. I will be reporting directly to Padma Singh and will work in tandem with acquisitions clerk Chris Phillips and fiction cataloger Loretta Coen. Kristin Lutz will be shadowing me and be my occasional assistant while she's a student in library grad school. [and so on]