YTD stands for Year-to-Date. It is a period starting from the beginning of the current year and continuing up to the present day. The year can start from January 1 (calendar year) or April 1 (financial year). In the financial world, YTD is used for publishing results of a business activity or financial statements which is less than one year.

Simply put, YTD describes the return so far this year.

E.g.1) The YTD return of SENSEX is 20%, means that from January 1 of the current year to date, SENSEX has appreciated by 20%.

E.g. 2) YTD revenue of Company A Ltd. (whose financial year ends on 31st March 2013) is Rs. 300 crore, as of 15th December 2012. This means that the company earned Rs. 300 crore of revenue during the period from 1st April 2012 to 15th December 2012, i.e. during the 8.5 months period.

Many-a-times, companies (with March year ending) state YTD numbers as of 30th September 2012 (while publishing their half yearly numbers). This states financial results for the first six months of the financial year. 

Providing current YTD results, as well as YTD results for previous years as of the same date, allows users to compare the company's current performance to that of past periods. This is similar to comparing quarterly or annual results.