is the parser that generates the parse tree for the given input string with the help of grammar productions by compressing the terminals. It starts from terminals and ends upon the start symbol. It uses the rightmost derivation in reverse order. Bottom-up parser is classified into two types: LR parser: This is a bottom-up parser that generates the parse tree for the given string by using unambiguous grammar. It follows the reverse of the rightmost derivation. LR parser is classified into four types: LR(0) SLR(1) LALR(1) CLR(1) Operator precedence parser