Devoted to understanding the basics and fundamentals of investing

Warren Buffett is renowned for his annual letters to his shareholders. You can find all of his letters at Letters to shareholders of Berkshire Hathaway. You can find information on the company BRK.A here. 

One of the lessons your management has learned - and, unfortunately, sometimes re-learned - is the importance of being in businesses where tailwinds prevail rather than headwinds. 1977 Think of oil companies (tailwind) versus the US auto industry (headwind)

We select our marketable equity securities in much the same way we would evaluate a business for acquisition in its entirety. We want the business to be (1) one that we can understand, (2) with favorable long-term prospects, (3) operated by honest and competent people, and (4) available at a very attractive price. 1977

We prefer:
(1) large purchases (at least $5 million of after-tax earnings),
(2) demonstrated consistent earning power (future projections are of little interest to us, nor are "turn-around" situations),
(3) businesses earning good returns on equity while employing little or no debt,
(4) management in place (we can't supply it),
(5) simple businesses (if there's lots of technology, we won't understand it),
(6) an offering price (we don't want to waste our time or that of the seller by talking, even preliminarily, about a transaction when price is unknown).

We will not engage in unfriendly transactions. 1982

Both our operating and investment experience cause us to conclude that "turnarounds" seldom turn, and that the same energies and talent are much better employed in a good business purchased at a fair price than in a poor business purchased at a bargain price. 1979

Assume you spend identical amounts putting each of two children through college. The book value (measured by financial input) of each child's education would be the same. But the present value of the future payoff (the intrinsic business value) might vary enormously - from zero to many times the cost of the education. So, also, do businesses having equal financial input end up with wide variations in value. 1983

...in all of our investments, we look to business performance, not market performance. If we are correct in expectations regarding the business, the market eventually will follow along. 1984

Unrestricted earnings should be retained only when there is a reasonable prospect - backed preferably by historical evidence or, when appropriate, by a thoughtful analysis of the future - that for every dollar retained by the corporation, at least one dollar of market value will be created for owners. 1984