What is strategy?
In general terms, a strategy is a plan to achieve a goal/objective within a given context/environment (tweet this). Strategy (as an activity) is the formulation of such plans.
What is business strategy?
In business strategy, the goal is usually variously defined in terms of growth, profit, sustainable value creation or something similar, or some corporate mission or vision statement. The context is the competitive, regulatory, technological, customer, etc environment in which the business operates, as well as it internal capabilities, resources, strengths and weaknesses. Furthermore, given constrained resources and limited executive attention, business strategies are often as much about defining what a business will do to achieve its goals as it is about defining what the business will NOT do in order to achieve sufficient focus.
What is competitive strategy?
Competitive strategy adds to this by recognising that there may be other players / businesses on the field with similar or competing goals which need to be out-maneuvered in order to achieve the business's goal.
What is marketing strategy?
Marketing strategy is a slight variant which starts from the position that the goal is to satisfy customers' needs. Whilst that is technically a narrower definition than business strategy, in practical terms, it is difficult to separate that satisfaction of customer needs from the sustainable achievement of just about any other business objective. For this reason, the lines between business, competitive and marketing strategy are easily blurred. However the broader definition of business strategy recognises that there are courses of action that can be pursued to make a business more successful which have little or no impact on what the customer experiences (at least in the short term).
For the reasons described above, business strategy invariably incorporates both competitive and marketing strategy.
Other types of strategy
There are, of course, lots of other types of strategy. Military strategy, for example, is a form of competitive strategy unrelated to either business or marketing strategy. So to are the strategies one might employ to win a game of chess or cricket. One might also have a weight loss or fitness strategy with no element of competitive, business or marketing strategy.
In all but the simplest contexts, successful strategies must recognize that the context is changing rather than static. Strategy must therefore be able to respond to, if not anticipate or even shape, such changes in the context.
Strategies, which are 'clever' are often considered more strategic than those that rely on brute force (size, amount of spend and effort, etc.). Complexity should not be mistaken for cleverness, and great strategies are often deceptively simple. For example, in the film 'A beautiful mind' John Nash famously advised his friends to always ask the second prettiest girl in a group out for a date, as she was more likely to appreciate the attention and accept. A very simple strategy, indeed (although I have always wondered if he shared this strategy with his friends so that they'd all pursue the second prettiest girls leaving him free to pursue the prettiest girls himself - which would be a neat feat of competitive strategy!)
Strategies can be good, that is, likely to achieve the goal even as the environment changes around it, or poor, that is, unlikely to achieve the goal and/or too static in the face of the changing environment. Good strategy is usually based on a thorough analysis of the context and capabilities. A thorough and complex analysis can just as easily result in a simple yet ingenious strategy (see, for example, my post on how to Analyse the Business and its environment.)
Strategies can be subdivide, for example, into short, medium and long term strategies, or into brand, IT, HR, financial, etc. strategies. Ideally,such sub strategies should all remain aligned as part of an overarching strategy (although my experience is that such alignment is not always achieved).
What are tactics?
Related, and yet different, tactics are unplanned adjustments to a strategy in response to unplanned for developments, and which are required in order to get a strategy back on track (without fundamentally changing the underlying strategy).
Strategy provides a context for the long-term, big picture thinking required in order to make trade-offs and sacrifices. Think, for example, of a chess player sacrificing a pawn in order to achieve some greater advantage.
Strategy itself is a relatively simple concept. The methods of achieving strategy, may be complex and varied, but at the end of the day, the objective is very simple: a plan to achieve an goal within a given context.