Block from U+0000 to U+007F. This block was introduced in Unicode version 1.1 (1993). It contains 128 codepoints.
The Wikipedia provides the following information on block Basic Latin:
The Basic Latin or C0 Controls and Basic Latin Unicode block is the first block of the Unicode standard, and the only block which is encoded in one byte in UTF-8. The block contains all the letters and control codes of the ASCII encoding.
The Basic Latin block was included in its present from version 1.0.0 of the Unicode Standard, without addition or alteration of the character repertoire.