entire module into memory if it has not yet been importedregardless of how many names it copies out of the file there is no way to load just part of module file ( just one function)but because modules are byte code in python instead of machine codethe performance implications are generally negligible potential pitfalls of the from statement because the from statement makes the location of variable more implicit and obscure (name is less meaningful to the reader than module name)some python users recommend using import instead of from most of the time ' not sure this advice is warrantedthoughfrom is commonly and widely usedwithout too many dire consequences in practicein realistic programsit' often convenient not to have to type module' name every time you wish to use one of its tools this is especially true for large modules that provide many attributes--the standard library' tkinter gui modulefor example it is true that the from statement has the potential to corrupt namespacesat least in principle--if you use it to import variables that happen to have the same names as existing variables in your scopeyour variables will be silently overwritten this problem doesn' occur with the simple import statement because you must always go through module' name to get to its contents (module attr will not clash with variable named attr in your scopeas long as you understand and expect that this can happen when using fromthoughthis isn' major concern in practiceespecially if you list the imported names explicitly ( from module import xyzon the other handthe from statement has more serious issues when used in conjunction with the reload callas imported names might reference prior versions of objects moreoverthe from module import form really can corrupt namespaces and make names difficult to understandespecially when applied to more than one file--in this casethere is no way to tell which module name came fromshort of searching the external source files in effectthe from form collapses one namespace into anotherand so defeats the namespace partitioning feature of modules we will explore these issues in more detail in the section "module gotchason page (see probably the best real-world advice here is to generally prefer import to from for simple modulesto explicitly list the variables you want in most from statementsand to limit the from form to just one import per file that wayany undefined names can be assumed to live in the module referenced with the from some care is required when using the from statementbut armed with little knowledgemost programmers find it to be convenient way to access modules module usage