Sometimes, when writing LaTeX documents, we find out lines too long, the so-called "overfull" lines, because LaTeX does not correctly divides words. To fix this, there are three parameters we can change: \pretolerance, \tolerance and \emergencystretch.
\pretolerance is used to tell the processor when there is too much space between words, and an attempt should be made to hyphenate some of them; \tolerance is used to indicate when there is too much space even after breaking words.
If we want to avoid breaking words, and avoid having too long lines, we have to use a very high value for \pretoletance. An “infinite” tolerance is represented by the value 10000.
In order to change its value, we have to add the line: