Short answer: A technical indicator is a preset mathematical formula applied to past price, volume, or open-interest data (open interest counts derivative contracts that are still outstanding) to produce signals about trend, momentum, or likely future price moves. Indicators are grouped by where they sit on a chart and by whether they lead or lag price, and each group has trade-offs.
Last reviewed: 14 November 2026
At a glance
| Term | Category | Key point |
|---|---|---|
| Overlay | Chart placement | Sits on the price chart and uses the same scale as price |
| Oscillator | Chart placement | Moves within a bounded range in a separate panel below the chart |
| Leading indicator | Timing | Tries to flag a reversal or new trend before it happens, but often gives false signals |
| Lagging indicator | Timing | Confirms a trend only after it has already started |
| Relative Strength Index (RSI) | Oscillator | Ranges from 0 to 100 and is used to spot overbought and oversold conditions |
| Volume indicator | Confirmation | A sharp rise in volume on a breakout suggests strong buying interest |
What does a technical indicator actually take in?
An indicator takes historical data as its input. That data is usually price, volume, or open interest, and the indicator’s formula turns it into a single line or reading. Traders then read that output as a clue about trend, momentum, or where price may go next.
The important word is “past.” Every indicator is calculated from data that has already been recorded. It cannot see orders that have not yet been placed, news that has not yet broken, or the decisions of institutions that have not yet acted.
How are indicators placed on a chart?
Indicators are commonly split into two groups based on where they appear. Overlays sit directly on the price chart and use the same scale as price, so a line drawn from them can be read against the actual price levels.
Oscillators move within a bounded range and are shown in a separate panel below the price chart. Because they have their own scale, they are easier to read for overbought or oversold levels than for exact price levels.
Are leading or lagging indicators more useful?
Leading indicators try to flag a reversal or a new trend before it happens. The catch is that they often give false signals, meaning they point to a change that does not follow through.
Lagging indicators take the opposite approach. They confirm a trend only after it has already started, so they are slower but tend to give fewer early warnings that turn out to be wrong. Choosing between the two means accepting either earlier signals with more noise, or later signals with more confirmation.
How does the RSI work?
The Relative Strength Index (RSI) is an oscillator that ranges between 0 and 100. It is used to spot overbought and oversold conditions, meaning periods when a security’s price has moved far in one direction relative to its own recent behaviour.
The RSI measures a security’s internal price strength. It does not compare two securities against each other, so it can be read on a single stock or index without a second instrument. An overbought reading describes a condition; it does not by itself say when the price will turn.
How do volume indicators confirm a price move?
Volume indicators help confirm whether a price move has real participation behind it. A sharp rise in volume on a breakout, where price moves above a recent range, suggests the move has strong buying interest and possible further upside.
Hypothetical example, with all figures invented for illustration: a stock in the Indian market usually trades 1,00,000 shares a day. On a breakout day it trades 2,50,000 shares. Dividing 2,50,000 by 1,00,000 gives 2.5, so volume is 2.5 times its usual level. A volume reading alone does not confirm the breakout will continue, so it is usually read alongside the price action itself.
Why does this explainer cover only some of the twenty?
A complete list of twenty indicators would need each formula, its inputs, and its typical behaviour checked against reliable sources. This explainer keeps to the points that have been verified, so it covers the classification system and two specific tools in depth.
The framework here still applies to most of the others. For any indicator you come across, ask whether it is an overlay or an oscillator, whether it leads or lags, what data it uses, and how often it has given false signals.
What are the main risks of relying on indicators?
The main risk is false signals. A leading indicator can point to a reversal that never arrives, and a lagging indicator can confirm a trend after much of the move has already happened.
A second risk is that every indicator is built from past data. A formula that described a market well in one period may describe a different period poorly, and the output of one indicator on its own rarely settles a question about price.
Frequently asked questions
Is a trading indicator a prediction of future prices?
No. An indicator is a preset formula applied to past price, volume, or open-interest data, and it produces signals about trend, momentum, or likely future moves. Those signals are clues, not guarantees.
What is the difference between an overlay and an oscillator?
An overlay sits on the price chart and uses the same scale as price. An oscillator moves within a bounded range and appears in a separate panel below the chart.
Does a leading indicator always warn before a trend change?
No. Leading indicators try to flag a reversal or new trend before it happens, but they often give false signals.
Does RSI compare one stock with another?
No. The RSI measures a security’s internal price strength, oscillating between 0 and 100, rather than comparing two securities.
Sources and last check
Facts in this article were checked against the sources below on 14 November 2026. Rules and figures can change; check the primary source before acting.
- groww.in (broker education)
- zerodha.com (broker education)
- upstox.com (broker education)
- kotakneo.com (broker education)
This article is general information, not investment advice. MyFinanceBandhu is not a SEBI-registered investment adviser.