Gluing Lines in Visual Mode
To Glue the next line to the current line, use a G in column 3 or 4. To Glue two lines with a space inserted at the joint, use GJ in columns 3 and 4.
To glue “pairs” of lines within a block, use GG to mark the start and end of the block.
By default, G and GG append text after the last nonblank character in a line, but it is also possible to glue text to specific columnar fields. You do this by inserting a field separator at the start of each field (mark the first line only). The default field separator is the tilde (“~”), but you may override this with Set Vis Field. If you specify three fields, G glues the next three lines to the first line. GG glues the next three lines to the first line, and then go on to the next group of four lines. If the precise column number where each field starts is important to you, insert the field separators from right to left, since each one that is inserted shifts the column numbers that follow off by one more.