WDI is online through a couple of links.  Try the main one first and then the other one as an alternate.

The accompanying reports are available in books and by PDF download back to 2005. 

For reports before 2005, you will need to look at real print books in the library.

Word of advice: use the reports to accompany the online database.  Dropped series do not appear in the current online version.  It is also much easier to use the online database if you use the reports alongside.

The World Bank’s World Development Indicators (WDI) includes over 1000 time series for over 200 countries covering economic, social, and environmental indicators.

Read more about the World Bank's Open Data Initiative at the home page and also be sure to visit the World Bank's open data catalog for over 2,000 indicators from databases such as Global Development Finance and African Development Indicators.

WDI is used by nonprofit, academic, and government researchers to compare data relevant to development across countries.  The database provides definitions and sources for each variable.

Coverage: from 1960-present but varies by indicator and country.

Topic Areas: Economic Policy & Debt, Education, Environment, Financial Sector, Health, Infrastructure, Labor & Social Protection, Poverty, Private Sector & Trade, Public Sector.

Sample Indicators: foreign direct investment (net inflows, % of GDP), literacy rate, adult total (% of people ages 15 and above), electricity production (kWh), stocks traded (total value, % GDP), health expenditure (private, % GDP), rail lines (total route-km), labor force with primary education (% of total), GINI index, ease of doing business index (1 = most business-friendly regulations), cash surplus/deficit (% of GDP).

Definitions: Over 300 indicators are defined on this page and the remaining are defined and sourced within the database when you click on the "Notes" button, which is in the middle-right of the query box. 

Search the database by simple word or browse by topic area.  If you are going to search by word, be sure to you are using the same terminology as WDI.  The browse-by-topic function is a better bet for you if you don't know the precise terminology (e.g. a search for "FDI" is not correct; you have to search for "foreign direct investment").

You could think of the World Bank as the curator of WDI.  That is, WDI are a collection of indicators representative of how the World Bank defines development.  Researchers take a variety of approaches when measuring development.  This Gouldguide for Professor Myint's Approaches to Development provides additional sources to consider for this question of development definitions and measures.