Wall Street insiders like to speak in terms of earning Alpha and Beta. Beta is systematic market exposure to the economy through investments traded on Wall Street. Earning Beta is getting "The Market Rate of Return", which includes all capital appreciation (price changes) plus any income (e.g., dividends, interest, & rents). Beta can be either a positive or negative value — in most years the market is up, but there are bear market years too. The easiest way to earn Beta is to just mindlessly own "The Market", say via an Index ETF like SPY or VT, in both good times and bad; and if you hold this position for many, many years, you can expect to earn something like 8 to 10% compounded annually, if the future is like the past.
Earning Alpha, which can also have a positive or negative return, is any trading/investing strategy applied to market-based investments that allows you to enhance The Market Rate of Return. The simplest example of an Alpha trading strategy has you buying The Market (taking a Beta position) when the broader market trend first turns bullish (the market is trading at a discount to the economy's long-term growth prospects) and selling (exit the position) when the broader market trend has run its course (is now trading at a premium to the longer-term economy's ability to grow) — this is simply taking advantage of the economy's natural boom-and-bust (recovery-and-recession) business cycles.
We live in a growth-biased economy, we can expect the price (value) of most ownership based investments (e.g., stocks) to appreciate at the growth rate of the underlying business, plus profits paid out from operations (yield), plus any inflation, plus or minus any change in the price multiplier (an increase or decrease in the P/E multiple, which is the market premium paid for a future stream of earnings). This is just an economic fact of life! Over the long run, this has been about 8% for large-cap stocks. The realized total return for these stocks over this period has been closer to 10% because the price/earnings multiple has gone up a little. It seems that investors have been willing to pay, on average over time, a growing P/E multiple for greater liquidity. P/E multiples will expand and contract based on investor’s greed and fear. The rate of return for small-caps is generally higher because they are riskier; but that value also suffers from a greater survivorship bias (retail investors should only own issues in this asset class via a fund to avoid a total loss of investment). Debt instruments (e.g., bonds), which are perceive to be safer than stocks, pay on average a percentage point or two less than a comparable stock.
Unfortunately, there are two uses of the term Beta on Wall Street. The first use was introduced above and refers to the whole market (systematic risk), which is generally expressed as a broader market index, like the S&P 500, which is an idealized mathematical number that does not include any real-world transaction costs. The second use of the term Beta refers to a correlation multiplier applied to an individual issue (security) to indicate a measure of the volatility of that issue relative to the broader market index. If an issue is perfectly correlated, it moves with the market, the issue's Beta multiplier is equal to 1. If the issue is correlated and twice as volatile, the issue moves twice as far in the same direction as the market, Beta is then set to 2. And if for every point the market moves up, the issue move down one point, Beta is -1; and so on.
Your expected rate of return on any individual issue should be the Market Rate * Beta of that issue + any Alpha you can bring to the position – your trading expenses.
There are a couple of points that need to be considered about funds and managers that promise or advertise a high Alpha delivery. If they're making or expect to make more than the market rate of return, you need to understand the risks associated with that Alpha promise; and the real-world basis for that alpha, which is often the result of a properly capitalized short-lived opportunity that may not be consistently repeated over time. There are good money manager who can earn that extra alpha; but when the extra alpha is unrealized, one of two things has to happen to return: 1) the yield must come down (i.e., the actual yield follows the actual alpha), or 2) your higher yield is maintained only because the fund manager is returning some of your principal (taking value out of the fund), which is not always a bad thing (focus on NAV, does it grow or contract over time — avoid funds with an NAV that does not track their benchmark index over time).
In any given year, most 70 to 80% on average, professional money manager underperform the market because the market is an idealized value, real-world managers have real-world costs, are rarely able to get the best prices because of their size (professional day-traders see these elephants buying and selling in size and front-run their operations), and because they're entitled to a fee for service, which can often consume a point or two from your total return. That’s why owning a passively managed index fund is often the best choice for retail investors who want to earn just beta — you get the market rate of return for the lowest fee possible.
Efficient market theory says we should not try to time the market because the market is just too efficient — it always reflects the sum of all known, including speculative, information. Whenever any new information hits the tape the market jumps in response. This implies that trading profits cannot be earned. In fact, they can be earned, just not consistently. The market is pretty darn efficient; but it is not perfectly efficient and often overreacts. There are in fact opportunities to earn Alpha; and most of the opportunities available to the retail investor reside in the area of playing the typical overreaction to news and commentary relative to the rationally economics (buy at discount prices and selling at premium prices when the market is overly bullish or bearish relative to longer-term business fundaments).