Assessment is a comprehensive, systematic and continuous activity. A culture of assessment is an ongoing process whereby institutional faculty and staff know and care what assessment results are produced, how these relate to desired outcomes (institutional / organization / programmatic), and are committed to using results for continuous improvement.
Large-scale surveys exist to gather information at the organizational or institutional level, but so do many tools that you can profitably use to gather informal data on information literacy as well as particular aspects of your library.
Are students learning? Is your information literacy program successful? How do you know?
Are users satisfied with your library programs and services? The building? How do you know?
The process of data collection does not have to be long or arduous. Polls and surveys are useful for gathering data in a variety of ways. The assessment tools below can be used in the classroom or on webpages for instant responses or over a period of time.
Course mapping. Matching the student learning outcomes of a required course to the program learning outcomes of the degree program.
Formative assessment. Measures what students are learning and allows you to modify your teaching mid-stream.
Goals. Broad statements that describe the overarching long-range intended outcomes of an administrative unit. These are usually not measurable and are primarily used for general planning.
Learning objective. A learning objective is a specific statement that describes what the student is to learn, understand, or to be able to do as a result of a lesson or a series of lessons. (Synonymous with Outcomes.)
Rubric. A rubric is a chart or plan that identifies criteria for evaluating a piece of a student's work, be it an essay test, a paper, or some other student production.
Summative assessment. Measures what students have learnt and includes capstone projects and presentations.
Library Assessment in Higher Education, 2nd Ed by 
An Action Plan for Outcomes Assessment in Your Library by 
The Quality Infrastructure: Measuring, Analyzing and Improving Library Services by Gariepy, Laura W., Jennifer A. Stout, and Megan L. Hodge. "Using Rubrics to Assess Learning in Course-Integrated Library Instruction." portal: Libraries and the Academy 16, no. 3 (2016): 491-509.
Kiel, Stephen "Mike", Natalie Burclaff, and Catherine Johnson. "Learning by Doing: Developing a Baseline Information Literacy Assessment." portal: Libraries & the Academy 15, no. 4 (2015): 747-766.
Luther, Michael. "Total Library Assessment." Journal of Library Administration 56, no. 2 (2016): 158-170.