Volatility and risk are related but not the same thing, and mixing them up is a common source of confusion. Understanding the difference makes lists of fast-moving assets much easier to interpret.
Volatility describes how much and how quickly an asset's price moves. A stock that moves one percent on a typical day has low volatility, while one that swings ten percent has high volatility. It is measured in several ways, often as the standard deviation of daily returns, but the idea is simple: bigger swings mean higher volatility.
Risk, in everyday terms, is the chance of losing money or failing to reach a goal. High volatility raises that chance because large down moves are as likely as large up moves, and because a volatile asset may be at a low point exactly when you need the money. But some risks have nothing to do with volatility, such as a company failing, fraud, or an exchange being hacked.
Small companies and small coins have fewer buyers and sellers, so each trade has more effect on the price. Their prospects are also more uncertain, which means news can change their value quickly. This is why UpTicker's focus on stocks and coins under $5 leads to a list full of fast moves, and why each section carries a reminder about risk.
You cannot control the market, but you can control how much of your money sits in any one thing. A common guideline among cautious investors is to keep speculative positions small enough that a total loss would not damage their finances. If a single position is so large that you would lose sleep over it, it is probably too large.
Spreading money across different assets reduces the effect of any single failure. Holding twenty speculative small-cap stocks is not real diversification if they all react to the same news, but combining different kinds of assets can make a portfolio's results smoother over time.
Money you need within a year should generally not be in volatile assets, because there may not be time to recover from a drop. Money you will not touch for decades has more room to ride out swings. Matching the asset to the time frame is one of the most useful habits you can build.
Fast-moving markets invite quick decisions, and quick decisions made from fear or excitement are often poor ones. Writing down in advance why you are buying and what would make you sell can help you avoid reacting to every move.
A screener can show you where the action is. Understanding risk is what helps you decide whether to take part at all.