Dynamic problems in computational complexity theory are problems stated in terms of the changing input data. In the most general form a problem in this category is usually stated as follows:

• Given a class of input objects, find efficient algorithms and data structures to answer a certain query about a set of input objects each time the input data is modified, i.e., objects are inserted or deleted.

Problems of this class have the following measures of complexity:

• Space – the amount of memory space required to store the data structure;
• Initialization time – time required for the initial construction of the data structure;
• Insertion time – time required for the update of the data structure when one more input element is added;
• Deletion time – time required for the update of the data structure when an input element is deleted;
• Query time – time required to answer a query;
• Other operations specific to the problem in question

The overall set of computations for a dynamic problem is called a dynamic algorithm.

Many algorithmic problems stated in terms of fixed input data (called static problems in this context and solved by static algorithms) have meaningful dynamic versions.