- A - Attention (Awareness): attract the attention of the customer.
- I - Interest: raise customer interest by focusing on and demonstrating advantages and benefits (instead of focusing on features, as in traditional advertising).
- D - Desire: convince customers that they want and desire the product or service and that it will satisfy their needs.
- A - Action: lead customers towards taking action and/or purchasing.
Using a system like this gives one a general understanding of how to target a market effectively. Moving from step to step, one loses some percent of prospects.
AIDA is a historical model, rather than representing current thinking in the methods of advertising effectiveness.
The term and approach are commonly attributed to American advertising and sales pioneer, E. St. Elmo Lewis. In one of his publications on advertising, Lewis postulated at least three principles to which an advertisement should conform:
The mission of an advertisement is to attract a reader, so that he will look at the advertisement and start to read it; then to interest him, so that he will continue to read it; then to convince him, so that when he has read it he will believe it. If an advertisement contains these three qualities of success, it is a successful advertisement.
According to F. G. Coolsen, "Lewis developed his discussion of copy principles on the formula that good copy should attract attention, awaken interest, and create conviction." In fact, the formula with three steps appeared anonymously in the February 9, 1898 issue of Printers' Ink: "The mission of an advertisement is to sell goods. To do this, it must attract attention, of course; but attracting attention is only an auxiliary detail. The announcement should contain matter which will interest and convince after the attention has been attracted" (p. 50).
The importance of attracting the attention of the reader as the first step in copy writing was recognized early in the advertising literature as is shown by the Handbook for Advertisers and Guide to Advertising:
The first words are always printed in capitals, to catch the eye, and it is important that they should be such as will be likely to arrest the attention of those to whom they are addressed, and induced them to read further.
A precursor to Lewis was Joseph Addison Richards (1859–1928), an advertising agent from New York City who succeeded his father in the direction of one of the oldest advertising agencies in the United States. In 1893, Richards wrote an advertisement for his business containing virtually all steps from the AIDA model, but without hierarchically ordering the individual elements:
How to attract attention to what is said in your advertisement; how to hold it until the news is told; how to inspire confidence in the truth of what you are saying; how to whet the appetite for further information; how to make that information reinforce the first impression and lead to a purchase; how to do all these, - Ah, that's telling, business news telling, and that's my business.
Between December 1899 and February 1900, the Bissell Carpet Sweeper Company organized a contest for the best written advertisement. Fred Macey, chairman of the Fred Macey Co. in Grand Rapids (Michigan), who was considered an advertising expert at that time, was assigned the task to examine the submissions to the company. In arriving at a decision, he considered inter alia each advertisement in the following respect:
1st The advertisement must receive "Attention," 2d. Having attention it must create "Interest," 3d. Having the reader's interest it must create "Desire to Buy," 4th. Having created the desire to buy it should help "Decision".
The first published instance of the general concept, however, was in an article by Frank Hutchinson Dukesmith (1866-1935) in 1904. Dukesmith's four steps were attention, interest, desire, and conviction. The first instance of the AIDA acronym was in an article by C.P. Russell in 1921  where he wrote:
An easy way to remember this formula is to call in the “law of association,” which is the old reliable among memory aids. It is to be noted that, reading downward, the first letters of these words spell the opera “Aida.” When you start a letter, then, say “Aida” to yourself and you won’t go far wrong, at least as far as the form of your letter is concerned.
Purchase Funnel 
Since the early 1960's, AIDA has frequently been illustrated in the diagrammatic format of a funnel, indicating that a larger quantity of potential purchasers become aware, then a smaller subset becomes interested, and so on. It is often referred to as a "purchase funnel," “customer funnel,” “marketing funnel,” or “sales funnel.” 
New Developments 
- S - Satisfaction - satisfy the customer so they become a repeat customer and give referrals to a product.
One significant modification of the model was its reduction to three steps (CAB):
- Cognition (Awareness or learning)
- Affect (Feeling, interest or desire)
- Behavior (Action).
Along with these developments came a more flexible view of the order in which the steps are taken, suggesting that different arrangements of the model might prove more effective for different consumer-to-product relationships.
Additionally, as experts have examined this theory more defined practices and theories have been developed including the T.I.R.E.A. scale that focuses on breaking down the decision making process into more defined components. Each step focuses on a progressive journey through the decision making process.
- T - Thought
- I - Interest (Desire)
- R - Risk (Evaluation)
- E - Engagement
- A - Action
The Thought portion of the decision making process can occur randomly and be stimulated by a variety of stimuli but generates little of no attention by an individual. It simply creates an awareness of something but generate little or no interest. Similar to seeing food after one has become full after a meal... one may be aware of the food that is there but there is little need or interest in obtaining it.
Interest occurs when one wants or needs something - hunger is an example. The level of interest (or desire) increases as hunger and or the wants and desires increase.
Risk and its evaluation occur as interest increases. One may desire steak but withhold obtaining it due to cost, or other reasons (such as health related issues, etc.)
Engagement - An emotional response when Interest and Desires exceed Risks.
Action - A physical response to obtain what one wants and desires and is willing to assume the risks and/or costs in obtaining it.
Cultural references 
The character Blake in the film Glengarry Glenn Ross by David Mamet makes a noteworthy reference to AIDA. A minor difference here is that the D in Blake's motivational talk is defined as decision rather than desire, presumably implying that the third step not only imbues the customer with the want of the product but also willing to commit themselves positively to the purchase.
- "Catch-Line and Argument," The Book-Keeper, Vol. 15, February 1903, p. 124. Other writings by E. St. Elmo Lewis on advertising principles include "Side Talks about Advertising," The Western Druggist, Vol. 21, February 1899, p. 65-66; Financial Advertising, published by Levey Bros. in 1908; and, "The Duty and Privilege of Advertising a Bank," The Bankers' Magazine, Vol. 78, April 1909, pp. 710-11.
- "Pioneers in the Development of Advertising," Journal of Marketing 12(1), 1947, p. 82
- London: Effingham Wilson 1854, Sixth Edition, p. 17
- "Well Told is Half Sold," The United Service. A Monthly Review of Military and Naval Affairs, Vol. 9 (N.S.), 1893, p. 8. An identical ad appeared in The Century of the same year.
- "The Bissell Prize Advertisement Contest," Hardware, March 1900, p. 44.
- "Three Natural Fields of Salesmanship," Salesmanship 2(1), January 1904, p. 14.
- C.P. Russell, "How to Write a Sales-Making Letter," Printers' Ink, June 2, 1921
- Peterson, Arthur F. (1959). Pharmaceutical Selling. Heathcote-Woodbridge.
- T. E. Barry, "The Development of the Hierarchy of Effects: An Historical Perspective," Current Issues & Research in Advertising 10(2), 1987, pp. 251-295. See also T. E. Barry & D. J. Howard, "A Review and Critique of the Hierarchy of Effects in Advertising," International Journal of Advertising 9(2), 1990, pp. 121-135.
- A. F. Sheldon, The Art of Selling, Libertyville 1911, p. 28: "Note these successive steps in the process of a selling transaction: 1. Favorable attention. 2. Interest. 3. Desire. 4. Action. 5. Permanent satisfaction. The second step depends on the first; the third on the second; and so on to the end."
- H. D. Kitson, Manual for the study of the psychology of advertising and selling, Philadelphia 1920, p. 21: "The steps to be taken by the seller at each stage are as follows: Stage I. Secure attention. Stage II. Hold attention Through Interest. Stage III. Arouse Desire. Stage IV. Create Confidence and Belief. Stage V. Secure Decision and Action. Stage VI. Create Satisfaction."
- J. A. Howard, Marketing Management, Homewood 1963; cf. M. B. Holbrook, "Howard, John A." in: P. E. Earl, S. Kemp (eds.), The Elgar companion to consumer research and economic psychology, Cheltenham 1999, p. 310-314.