Conclusions based on analogy occur both in the ordinary language of everyday life and in mathematics, as well as in some other sciences. In mathematics, analogy means that we have noticed a similarity between some objects and based on this similarity we have concluded that the objects have some other properties in common. In this work, we explained what analogy is and how important of a tool it is in making mathematical conclusions as well as connected it with other forms of thinking and deductioning. In the first part of the work, we described what analogy is in general, gave examples of false analogy and said a few words about Leonhard Euler. Then we studied the basis on which concluding using analogy can be carried out in mathematics. Then gave various examples and put special emphasis on analogy and generalization. We devoted the second part of the work to analogy in geometry, with an emphasis on the analogy within planimetry and stereometry. We devoted the third part of the work to analogy within teaching of mathematics (especially geometry). We said a few words about its importance in school education, students’ misconceptions, the purpose of analogy within technology and at the very end we gave three activities that can be applied in mathematics lessons.