A system, a computerized method, and a computerized service center for classification of items based on their attributes and on a classification scheme that is defined based on information pertaining to each item of a set of items, and which is indicative of: (a) a quantity of occurrences of the item in a sample; (b) a quantity of successful occurrences of the item in the sample; and (c) at least one attribute of the item with regard to at least one variable out of a set of variables.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A system for classification of an analyzing item, the system comprising: a storage apparatus, configured to store information pertaining to items out of a set of items, thereby to yield stored items, the stored information for each given stored item being indicative of: (a) a total quantity of occurrences of the given stored item in a sample; (b) a quantity of successful occurrences of the given stored item in the sample; and (c) one or more attributes of at least one variable characterizing the given stored item, wherein an occurrence of an item is regarded successful if it fulfills a predefined condition associated with a predefined outcome of the occurrence; and a processor, comprising: a classification scheme determination module configured to define a classification scheme comprising a plurality of classes for classifying items into classes, defining the classification scheme includes processing the stored information to assign a score to the at least one variable, the assigned score corresponding to a plurality of values corresponding to different attributes out of a plurality of attributes of the at least one variable, each value indicative of a number of successful occurrences of the stored items characterized by the same attribute; a class management module, configured to obtain for each class, out of the plurality of classes, a respective subset of the stored items by applying the defined classification scheme to the stored items, and to determine, with respect to each given class out of the plurality of classes, an outcome estimation value of the given class, the outcome estimation value indicative of the given class performance and based on a value indicative of successful occurrences of the stored items out of the subset of the stored items classified to the given class; and a performance analysis module, configured to classify the analyzing item by applying the defined classification scheme to attributes characterizing the analyzing item, and to assign to the analyzing item a performance assessment value being a function of outcome estimation value determined for a class to which the analyzing item is classified. 2. The system of claim 1, wherein the stored items and/or the analyzing item are representative of at least one entity selected from a group consisted of one or more advertisements, one or more users, one or more audiences and one or more business entities. 3. The system of claim 1, wherein the items are keywords. 4. The system of claim 3, wherein the processor is further configured to use the performance assessment value assigned to the analyzing keyword for enabling selecting a price for bidding on the analyzed keyword. 5. The system of claim 3, wherein at least one variable characterizing a given keyword is a type of the given keyword and an attribute of said at least one variable is indicative if the given keyword represents a brand and/or a given brand. 6. The system of claim 1, wherein each occurrence is an impression, and each successful occurrence is a click. 7. The system of claim 1, wherein each occurrence is a click and each successful occurrence is a conversion. 8. The system of claim 1, wherein the processor is further configured to enable a selective application of an industrial process, wherein the selective application is responsive to the performance assessment of the analyzed item. 9. The system of claim 1, wherein the defining the classification scheme includes assigning a score to each attribute out of the plurality of attributes of the at least one variable, based on a number of occurrences of the stored items characterized by the attribute. 10. The system of claim 9, wherein the assigning of the score to each given attribute out of the plurality of attributes comprises computing the score to the given attribute based on at least one of: (a) a number of successful occurrences which are associated with the given attribute in a subset of the sample; (b) a number of unsuccessful occurrences which are associated with the given attribute in the subset of the sample; and (c) a total number of occurrences which are associated with the given attribute in the subset of the sample. 11. A computerized method for classification of an analyzing item, the method comprising: storing in a non-transitory storage media information pertaining to items of a set of items thereby yielding stored items, the stored information for each given stored item being indicative of: (a) a total quantity of occurrences of the given stored item in a sample; (b) a quantity of successful occurrences of the given stored item in the sample; and (c) one or more attributes of at least one variable characterizing the given stored item, wherein an occurrence of an item is regarded successful if it fulfills a predefined condition associated with a predefined outcome of the occurrence; defining a classification scheme comprising a plurality of classes and configured for classifying items into classes, wherein the defining the classification scheme comprises processing the stored information to assign a score to the at least one variable, the assigned score corresponding to a plurality of values corresponding to different attributes out of a plurality of attributes of the at least one variable, each value indicative of a number of successful occurrences of the stored items characterized by the same attribute; applying the defined classification scheme to attributes characterizing the stored items, thereby obtaining for each given class out of the plurality of classes a subset of stored items in the given class; determining, with respect to each given class out of the plurality of classes, an outcome estimation value of the given class, the outcome estimation value indicative of the given class performance and based on quantities of successful occurrences of items out of the subset of the stored items classified to the given class; classifying the analyzing item by applying the defined classification scheme to attributes characterizing the analyzing item, and assigning to the analyzing item a performance assessment value being a function of outcome estimation value determined for a class to which the analyzing item is classified. 12. The method of claim 11, wherein the stored items and/or the analyzing item are representative of at least one entity selected from a group consisted of one or more advertisements, one or more users, one or more audiences and one or more business entities. 13. The method of claim 11, wherein the items are keywords. 14. The method of claim 13, further comprising enabling selecting a price for bidding on the analyzed keyword in accordance with the performance assessment value assigned to the analyzing keyword. 15. The method of claim 13, wherein at least one variable characterizing a given keyword is a type of the given keyword and an attribute of said at least one variable is indicative if the given keyword represents a brand and/or a given brand. 16. The method of claim 11, wherein each occurrence is an impression, and each successful occurrence is a click. 17. The method of claim 11, wherein each occurrence is a click and each successful occurrence is a conversion. 18. The method of claim 11, wherein the quantities of successful occurrences are determined in accordance with one or more predefined pairs constituted by respective pre-condition and condition of occurrence. 19. The method of claim 11, further comprising enabling a selective application of an industrial process, wherein the selective application is responsive to the performance assessment of the analyzed item. 20. The method of claim 11, wherein the defining of the classification scheme includes assigning a score to each given attribute out of the plurality of attributes of the at least one variable, based on a number of occurrences of stored items characterized by the given attribute. 21. The method of claim 11, wherein the items are keywords and wherein the storing comprises storing in the storage apparatus for each given stored keyword out of a set of stored keywords information in which: (a) the total quantity of occurrences of the given keyword in the sample is indicative of a number of redirections of users which resulted from queries that included the given keyword within a sampled time frame; (b) the quantity of successful occurrences of the given keyword in the sample is indicative of a number of conversions resulting from the redirections; wherein the determining an outcome estimation value comprises determining, with respect to each given class of the plurality of classes a conversion-rate estimation, based on quantities of redirections of keywords out of a respective subset of stored keywords in the given class; wherein the assigning the score comprises assigning to an analyzed keyword which does not belong to the set of stored keywords a conversion-rate assessment which is based on a conversion-rate estimation of a class corresponding to the analyzed item. 22. The method of claim 21, further comprising updating an entry that is associated with the analyzed keyword in a bidding database based on the conversion-rate assessment, thereby facilitating cost reduction in a bidding process that depends on the analyzed keyword. 23. A computerized service center configured to facilitate: storing in a non-transitory storage media information pertaining to items of a set of items thereby yielding stored items, the stored information for each given stored item being indicative of: (a) a total quantity of occurrences of the given stored item in a sample; (b) a quantity of successful occurrences of the given stored item in the sample; and (c) one or more attributes of at least one variable characterizing the given stored item, wherein an occurrence of an item is regarded successful if it fulfills a predefined condition associated with a predefined outcome of the occurrence; defining a classification scheme comprising a plurality of classes and configured for classifying items into classes, wherein the defining the classification scheme comprises processing the stored information to assign a score to the at least one variable, the assigned score corresponding to a plurality of values corresponding to different attributes out of a plurality of attributes of the at least one variable, each value indicative of a number of successful occurrences of the stored items characterized by the same attribute; applying the defined classification scheme to attributes characterizing the stored items, thereby obtaining for each given class out of the plurality of classes a subset of stored items in the given class; determining, with respect to each given class out of the plurality of classes, an outcome estimation value of the given class, the outcome estimation value indicative of the given class performance and based on quantities of successful occurrences of items out of the subset of the stored items classified to the given class; classifying the analyzing item by applying the defined classification scheme to attributes characterizing the analyzing item, and assigning to the analyzing item a performance assessment value being a function of outcome estimation value determined for a class to which the analyzing item is classified.